So I set about to see what the limits of the AVX are in tracking (given a full moon night with lousy seeing, what else would I do?).
The results are shown below. I got polar aligned as well as I could and attempted to confirm that by slewing in RA with the shutter open (Regulus, upper left). I then tried several different exposure lengths unguided.* 60s seemed to be fine. 150s was okay if I would be willing to lose 20-40% of my subs (see one good 150s and one bad).
I then ran the PEC routine and employed that while guiding. 150s was no sweat. 300s was fine. 600s was fine. Finally, I've posted the one 900s exposure I recorded. It was at ISO 100 with a Canon T2i, f/6.3 reducer and Hutech LPAS filter. I confirmed the identity of the asteroid by recording images over a few hours (see Solar System forum if you're interested). The guider was the Orion Finder guider.
To be honest, I'm about as happy as I can be with this outcome. I was never able to get consistently good tracking with the CG5 over 5 minutes. Here I have round stars at 15 minutes. Hopefully, it wasn't just a fluky good night.
* what is it with the desire to run unguided? AP seems pretty complicated no matter what you do, I figure you may as well make it slightly more complicated and guide, thus ensuring a more likely happy outcome. YMMV, I suppose.