Well, this 6" achro is pretty much dead in the water for now anyway.
Looking at the 4.7? 120 f8.3. Which I guess would be a little slower than a 150 with similar focal length ratio? I'll have to look up the formula for that.
For new, Celestron seems to be the only game in town in f/8.3, with the Omni XLT.
The CG4 tripod that the XLT 120 comes with is probably a little light.
The Meade LX85 looks to be higher rated at 33 pounds, for not a lot more money. $699 with Go-to. But their 127 scope package($999) is an f5.8.
And their rep with Go-to hasn't been stellar.
As far as grab and go. I don't know that the 8se or 120 f/8 would be terribly inconvenient. Sure the 4" would be easier to carry to the car. But too big for a backpack or carry-on.
And the 120 is already a substantial step down as far as portability from the 150 f/8.
But I won't rule out the 100mm. It does make sense as far as not overloading the smaller tripods. It might be right where I really want to be.
Not really interested in a newt right now..or a dob. Right or wrong. Eventually, a 12" sounds about right.
Oh.,..and MalVeauX, I love your solar photos. Makes me want to plan for attempting something like that. And I believe a few of those shots were taken with 120 and 150 achros if I'm not mistaken?
The 120mm F8.3 is a pretty good scope too, easier to mount than a 150mm F8, lighter, much easier to use in that way. It also has less CA, but it still has CA on bright objects. I have this scope too and visually I like it better than my 150mm F8, largely due to being light and less CA. I use it for planets mostly. I have a 120mm F5 (lots of CA) for low power DSO sweeping and love it for that job. But the 120 F8.3 is a good inexpensive way to get refractor views on planets and all that, plus deep space, without breaking the bank and is friendly to eyepieces with that long focal length.
The 120 F8.3 is still no slouch to mount though, typical mounts for 80~102mm fracs for grab & go are not sufficent for this scope. This scope is quite long and while a mount head can handle the weight, its not the weight that matters so much as the length. It generates a big moment arm and so it will bounce and wobble on lesser mounts and after mounting it on several things, it really does come down to the legs of the mount. For example I tried using the 120 F8.3 on a Twilight 1 (stock) and it was not usable, it simply couldn't handle it, it wobbled forever. I changed the legs to beefier legs and it improved but was still too much scope for that mount head. Well, I recently put that mount head into a cinder block pier and now the head of the Twilight 1 on a pier (no legs) can boss my 120mm F8.3 around, totally different mount head on a pier, the instability was the legs each time. Funny how that worked out.
The CG4 can hold the 120mm F8.3 totally fine with its head, but the weak point is the tripod/legs. I think if you want a pair of legs under a tripod for a 120mm F8.3 class scope, an EQ5 mount or Twilight II class mount really is unfortunately where you need to go if you want a smooth wobble free experience. I know that seems a lot for a mount for a cheaper scope, but these 120 F8.3's are no joke for mounting and while you can mount it on less, it will wobble and bounce on most heads with tripod legs and its all preference of course, but focusing a long focal length while it's bouncing around on a planet is no fun and by the time it settles it's out of the FOV. This scope behaves so nicely when mounted properly and it's a very pleasing view when its steady and held rigid.
A 102mm frac (F7 to F9) is a lot easier to mount. The AT102ED is a very friendly visual scope and easier to mount. Always a compromise.
Here's a 120mm F8.3 on a Twilight II next to a 200mm F6 Newt. The 120's are still big scopes and require rather beefy mounts for a pleasing experience (despite the weight, as they're light weight).
Here's the 120mm F8.3 on a Twilight I head mounted on a cinder block pier (cheap and extremely effective, bosses this scope around like a whole new mount when pier mounted) and a few examples of other scopes for reference (a 120mm F5 and a 127mm F12 Mak to show size differences):
So in the interest of having a mount that can handle the weight, length and size of larger scopes and still provide a nice pleasing experience, I would look into over-mounting them early on so if you change scopes you're not also changing mounts. Also, while still being portable and not requiring crazy setup or alignment stuff, you can look into a heavy duty alt-az mount with slow motion control. Check out a SkyTee2:
You can mount a 6" refractor on that, no problem. It'll handle a 8 inch newt too. It will handle 11 inch SCT. With a counter weight it will hold a 10" newt even.
Get a solid mount that is portable now and you'll no longer worry about what you can get in terms of a telescope and then just enjoy viewing with anything you want. No electronics to fail.