Good news!
I got it on the AVX, improved the collimation a bit, and it's better than I thought.
The weird intrafocal/extrafocal patterns persist, but I was able to split Eps. Arietis, which is a 1.4 arcsecond double. It's not a completely clean split, but it's pretty good. And once you get to that level, it's hard to say it's not the sky.
I'm guessing the optics aren't amazing (it probably has a bit of SA) but they're at least ok. It will be fine for deep sky and probably at least somewhat usable for planetary. I looked at Uranus and Neptune tonight and they both resolved into neat little disks. Actually, the disk for Uranus is one of the better ones I've seen - the seeing was actually pretty good tonight. I really got the feeling that "Yup, there's a disk, that's really a planet". So, not bad - but we can't really get an idea about the contrast until Jupiter and Saturn come back.
Also, the transfer to the AVX was nothing but an upgrade in just about every possible way. The AVX cannot only handle the 10", it is significantly more stable than the original Meade fork was (I was not expecting that). Goto worked, although it seemed a bit less accurate than usual (maybe because of the focal length?) The scope is much easier to transport now because there is no big scope + fork combo - the OTA, by itself, is pretty friendly to carry around, neither extremely heavy nor excessively bulky. The ergonomics are better because the fork can't get in the way of your body. I guess the finder is harder to get to, but with goto, you don't really use the finder much.
So, it's looking pretty good. I think it'll be a fun scope when the weather improves more. Tonight, during testing, I really appreciated having so much aperture on the AVX. It'll be nice to have a telescope on the AVX that doesn't just make me wish I was using a larger telescope.