I did a little "shoot out" on my balcony last night with my 11 Edge. Put it out with my 12.5 Portaball. The dob is just (as expected) ill suited to living on a balcony. It never got close to being cooled until after midnight, and the field of view is highly constrained. The edge with Tempest fans was putting up far better views a couple of hours earlier. Given that I am often in a similar situation to the OP, I do wonder whether I should keep the Edge 11, or down size to a 8".
The 8" would cool more quickly, and be great for quick views on my balcony. And obviously I keep the PB for my trips to the mountains. Decisions decisions. The views last night were awesome in my Edge11. Once cooled, they are fantastic. But then after midnight, the view of the double cluster, low in the sky and under heavy moon and light pollution was wonderful.
You can tell what a big-scope newbie I am because I had somehow erroneously concluded based on your earlier comments about the EdgeHD 11 + Tempest fans that the 12.5" Portaball would have the SCT beat cold (pun intended). Glad to see the Tempest fans are doing something good after all: I will be getting some "Fire Ball" red ones in the hope they match the red of the Avalon T-POD tripod .
Roughly what was the temp difference your scopes had to handle, and do you happen to have any experience with their Fastar fan and whether it further speeds up initial cooldown?
Given Sedat's and others' comments, the EdgeHD 8 is a solid choice as a companion scope to your PB for sure. Still, after seeing the hyper-fine lunar detail and the wide-ranging ability to resolve M13, as compared to my 123mm f/6 LZOS triplet, I'm not sure I'd want to take even a little step back, especially not since I enjoy using my Maxbright binoviewers with the big SCT. Also, that Power/Filter Switch diagonal is truly made for the EdgeHD 11: no worries with aperture reduction due to heavy in-focus requirements, and so provides a lot of light even with binoviewers. Absolutely spine-tingling using both eyes in my Maxbrights to watch a very resolved M13 slide past the FOV, let me tell ya ....
I was surprised to see that the Edge won too! But this is just one comparison, and in the worst of circumstances for the Portaball. I'm still getting the hang of fine tuning collimation, and the cooling was way off. I think having the shroud in place hobbled cool down big time.
The Edge does well when the seeing is good (like last night), and when the temperature delta is (I'd guess) less than 10F. Last night that would be close to what it had to contend with. Even then a defocused star at around midnight showed heat plumes. So it could have been better yet.
But outside of summer, the deltas here are surprisingly large (coastal California). My scope would be mid- 70s in its case inside, and then outside to mid-50s is very common. Just too much to deal with. Also the Edge being up on a tripod is presumably in a better position to cool down. But this is the location I use most. I typically go out there for a couple hours each night after work if the skies permit (my dark site is a 25 minute drive). The 11 Edge gives these kinds of views only rarely--the sky and temperatures have to really cooperate. So I do wonder whether I would get more good nights out of an 8 inch.
I have to agree on the views through binoviewers (I have the Denk with powerswitch). Breath taking. Even with a poor angle, I was able to start resolving craters in Plato. I've never tried before, but in the fleeting moments I believe I caught 5, or possibly 6. The PB was merely giving hints at 1 or 2.