I know it's not a fair comparison as the Trinovid is one generation behind it seems but it's a fine binocular and deserves to be tested against the latest and greatest. Furthermore it's all just my non-expert opinion, rather a user's perspective.
I did not find the Swaro to be that much brighter - it's barely noticeable and you have to look hard. However, Swaro EL 8.5x42 does represent colors better, very slightly. Sharpness: Leica is very, very sharp. However, Swarovski is just as fantastically sharp. If I had to use a sharpness reference standard, it would probably be Leica however, but it might be due to the many hours I spent with it. They are dead even with regards to resolution sharpness.
Brightness: Swaro wins here. It's hard to quantify. I heard one estimate that Swaro is 5% brighter.
Chromatic abberation: I haven't seen any in Leica. I have not seen any in Swarovski.
Flare control: Less in Swaro than Leica.
Edge to Edge sharpness is most excellent in Leica and just as good in Swaro. The sweet spot is huge in both.
So optics-wise, it's a win for Swarovski by a slim margin due to a very slight margin in brightness, and the extra 0.5 power. But I expected more brightness from Swaro.
Swarovski does resolve objects better due to 8.5x vs. 8x power albeit without increased shake as holding it is easier. I haven't been able to run tests with regard to Field of View and Depth of Field. Going by specs, FOV is the same. It seems what one does - so does the other. My score is 10 for Swarovski and 9.5 for Leica, pretty close.
Leica has a reassuring weight to it. It's a bit on the heavy side. I don't mind, as I think quality optics should weight something. If you want something light, get a sub $100 commodity optics from a major retailer. When I hold Leica, I don't think - oh , how heavy. I think, this is a wonderful quality bino. Swarovski however has perfect weight - not too heavy, not too light, just perfect. So here Swarovski wins, slightly due to the about 28 oz vs. 31 oz difference. Swaro scores a 10, Leica 8.5.
This is where Swarovski totally dominates Leica. The EL split design is so much easier to use. One thing I find questionable in Swarovski design is some metal on the inside part of the barrel. I wonder why they choose not to put the armor around it. It does get cold if you have to hold it in the winter. However, if it's that cold, should use gloves anyway.
One huge bonus over Leica is the objective cover. It's amazing Leica doesn't come with an objective cover to protect it against rain, snow, dust and damage. It's a no-brainer. The strap is longer in Swarovski than Leica. Ergonomically, Leica does have one big advantage: - Leica is considerably shorter in length and therefore more compact. When I first got the Trinovid, I couldn't believe how compact it was for 8x42. Longer length of Swaro is not necessarily a problem, it's actually easier to hold and easier to balance.
Ergonomics and user interface is a sound win for Swarovski. 10 vs 9.
Build quality, durability and longer-term reliability
Build quality seems basically identical but I would have to give a slight edge to Leica. There is just something intangible about it. I haven't dived under icy water with either one, nor have I dropped either one in a vulcano. Both are supposed to be waterproof, fogproof and shock proof. Both fulfil these claims.
Let's keep in mind that Leica has been around for decades, with the original Trinovid debuting in 1950's, while Swaro EL is a fairly new model entering the market circa 2000. Swarovski is as much obsessed with quality as Leica is and it shows but Leica has more experience and more R&D if I were to guess. The Trinovid has been discontinued after many incarnations but it in fact keeps living in the Ultravid body, which isn't a radical redesign (lighter body, better coatings), it's basically an updated Trinovid IMO. And that's perfectly fine.
I love Trinovid's rubber coating, it's very durable. Put some ArmorAll on it once in a while and it will look like new years from now. I haven't yet figured out what's best for EL's armor. So in this category, I have to rate Leica higher, 10 vs. 9.
The focus is much smoother, lighter and without backlash in Swarovski. Swaro has upgraded it's focus from the earlier, slower version (2.5 turns from close-up to infinity to about 1.5 turns, circa 2004) It's easier to dial in to the right focus without having to go back and forth like I do with Leica. Swarovski's focus seems to be slower than Leica's which is OK. I always found Leica's focus just a bit too fast, if they could slow it down 10%, that would be good. Leica's focus is a bit coarser than Swaro, you need to apply more pressure while Swaro is a one-finger kind of focus. This is both good and bad. It's bad because it takes more pressure to dial in to the right position but good thing about it, it's far less likely to be knocked out of a setting than Swarovski. I set Swarovski to infinity and it will sometimes change the focus seemingly on its own, when I take out from the case.
I will rate both at 10, they just have different features. As software developers say, "It's not a bug, it is a feature".
Focus override past infinity and Eye Relief:
Big win for Swarovski, it can focus past infinity to -6D while Leica can only do -4.5D (?) This means if you have myopia (Nearsightedness) of -5 diopters or worse and you are blind as a bat like me, you won't be able to use Leica without eyeglasses, but Swarovski you can. This is especially important for astro viewing. Swaro has twist-up eyecups which stay raised and offer an infinite number of heights. They don't offer click-stops. Leica has pop-up eyecups which offer just 2 positions: Totally down and totally up. In my experience, they provide just the right amount of eye relief in either position (down for glasses, up for usage without glasses.) I think Swaro's eye cups are superior as there is no possibility they will be accidently pushed down and you get to have many more settings. Great design idea.
Here, I rate Swaro at 10 and Leica at 5.
BTW, I am very disappointed that Leica did not fix this focus range "bug" in the newer versions of Trinovid, meaning the Ultravid, which seems to closely maintain its Trinovid roots. As far as I understand, ER, focus past infinity is basically identical to Trinovid's. Ultravid's can focus closer than Trinovid BA (which to me is irrelevant) but still has the same insufficient focus range. I suspect that to solve this problem, they would have to drastically redesign the whole thing instead of just updating it. Myself, I wish Leica would sacrifice some close-up focus and gain focus overtravel to 6D like Swaro or 7D like Zeiss. I care about using binos for astronomical purposes and other general usage like nature, not look at fleas on birds 10 ft away. As much as am impressed with Leica's optical perfection manifested in the Trinovid line, I will probably never buy one of the current models given so much viable competition.
Trinovid BA has worse close focus distance. To me it's utterly irrelevant, I am not into butterflies.
Eye relief is OK in Leica but greater in Swaro. They both can be used with eyeglasses. Swaro has an edge at 18mm vs. 15.5mm of Leica. I like that as I can see a bit more with Swaro and the edges seem sharper. I think I could switch my eyeglasses for a pair that would sit closer to the eyes, enabling Leica to offer just as good ER as Swaro. But I don't want to.
Without eyeglasses, the Swaro EL is more difficult to use because the eyecup does not extend as far as it does in Leica. Just to be certain, I measured the height that is gained by raising the eyecup:
Swarovski: 0.355" 9mm
Leica: 0.465" 12mm
So the difference, not surprisingly, is almost 3mm and that explains why Leica feels more comfortable with no possibility of blackouts. It's not that Swaro has too much ER, rather the eye cup doesn't rise high enough.
Swaro can be held carefully to avoid blackouts. One option is to upgrade the eyecup designed for more ER, like the eyecup from 8x50 SLC with a height of 0.505". Here as well as elsewhere, YMMV.
Swaro has hydrophobic "Neu" coatings on the external surfaces and do help with cleaning, dirt doesn't seem to stick to it. Another bonus is that they seem harder to scratch. IMO, the coating is great, far better than Leica's but IME is not actually hydrophobic. Rating: Swaro 10, Leica 5.
Leica: The hindge cover is plastic and seems like it would break if hit with something at just the right angle. Lack of objective covers. Weights slightly more than it should, although not really a problem. Ergonomics. Holding 8x42 Trinovid initially felt like holding a shoe box but eventually you get used to it.
Swarovski: The hindges are metal and seems like paint will eventually come off. Worse, in cold weather, that metal surface is cold! You have to put your gloves on, while in Leica's case, you don't. Leica has armored the entire surface leaving no exposed metal parts, Swarovski should have done the same.
In the modern world of manufacturing, outsourcing is the name of the game, and while Swaro EL is an optically outstanding bino, some of the accessories it comes with are highly questionable if not totally worthless.
First, the case that it comes with EL is totally worthless. The bino does not even fit in it when it has strap on it. Even if the eyecups are in the down position. It certainly wouldn't fit with the raised eyecups. Then, it doesn't offer any protection against impact, or moisture, or water. It's some kind of cheap nylon.
Worse, the eyecup cover. It's actually pretty nice in Leica, but in Swaro it's a horrible piece of plastic with some very sharp edges. It should be replaced with something. If you are tired or it's dark outside and misalign the eyecup, you can theoretically damage the lenses with a sharp, hard plastic edge.
It looks like one set of engineers designed the bino, then handed it off to another team which designed the stamped plastic ocular cap and the case, to the wrong specs. Oh well, in our day and age, "oursourcing" and cost-cutting is the name of the game. Get a better case.
Leica's soft leather case is better. It actually offers next to no protection against impact, but when not in use, it can be rolled up and put in a pocket, and that's a very cool thing IMO.
It's incredibly that Leica doesn't come with objective covers, it desperately needs one. I know you can improvise and get some elsewhere, but that's not the point.
Here, I give 8 to each as both have some weak spots.
Swarovski EL is considerably more expensive than Leica Trinovid. Twice as expensive in fact. Trinovid, while optically very slightly inferior - and even then equal to Swaro resolution or contrast wise but with poorer color representation, IMO. In terms of pure value, Swarovski is a poor deal while the Trinovid is a fantastic deal.
I rate Trinovid at 10, and Swaro at 7. On the used market, at least here in US, Trinovids consistently go for around 700-800, while Swaro EL usually twice that much, especially the 10x model. It's better, but not by a huge margin.
Swarovski wins. I will rate it at 9.5 versus 9.0 for Leica. It wins not due to optics IMO. Rather due to to better ergonomics, better focus range, better Eye Relief, objective covers and slightly better color representation (I reserve the right to revise this view upon more testing)
The Trinovid however is not even close to being obsolete and remains very capable even against the best, and a great buy at half the cost of Swaro. I prefer Swaro but if I had to use the Trinovid I would not be disappointed.