An update!
I spent about half an hour with the Peavey Ecoustic 112, and liked it pretty well. The effects were pretty good for what they were, the clean sound was pretty fine. Ran my Muff into it and it hated it; ran the Rat and was able to get an OK, not great sound, but feedback wasn't an issue.
Then on a whim I plugged into this weird amp I had never heard of that was sitting right next to it: a Barcus Berry SXL15. Solid state combo from the 70s that nobody at the shop knew anything about, and that I can't even find a picture of online (here's the bass version:
http://www.njuskalo.hr/glazbena-oprema/bass-amp-barcus-berry-oglas-5655754) This thing sounded amazing. Clean, not brittle, seemed perfectly balanced. And the acoustic into the Rat into the amp sounded great! Unfortunately I couldn't devote much time to it so I put a deposit down and went to my next destination.
Tried the Trace Elliot that I had high hopes for; was disappointed. Good features (XLR, channel blending) but the reverb was a joke and it just sounded a little thin. Tried an old Heathkit just for the fun of it, and went to my next stop, where I played a Fender Acoustasonic SFX. It wasn't bad; compared to the Peavey, the cleans were a little better, the effects a little worse and a lot less flexible. It did generate a lot of sound, but I was still left feeling kind of meh.
After that I was feeling overstimulated and hungry, so I decided to cut the gear mission short and eat a burrito. Had to race home to take care of the dog, so I probably won't get back to the shop to play the BB more, but I'm pretty certain I'm gonna steal it (not literally) for $325, not including whatever I can get for my Roland.