Great find, John. I loved this comment:
There is no substitute for direct experience. Try it. It will feedback like a bitch and sound awful you will then have learned first hand.
Have done that and agree 100% and the guitar I was using was a thinline Martin Road model, designed for stage use.
My direct experience of acoustic amps is as follows:
Behringer Ultracoustic 1800 - current amp - not recommended! Bought for power as I was gigging in a full band situation at the time, but reliant on backline, rather than a PA. It's rated as 180W, but is more like 40W!! Nice clean sound, but the output effects other than subtle reverb are generally next to useless. The feedback control is good though, as is the compressor.
Marshall - my brother likes his, but wishes he'd bought a 50, rather than a 25.
Carlsbro - dabbled with one of the late 80s models. Don't think they make them anymore, but they are available second-hand if someone wants to sell their's - very good sound for the money.
Vox - tried one of the new valve preamped ones. Nice sound at low volumes, but had problems with feedback control.
Schertler David - tried my Martin through it when I was buying it - VERY nice!!
I have always heard great things about those AERs, but I think I'd be more likely to get a small PA if I were gigging often: there are some good bargains to be had with a pair of powered speakers and a little mixer. The DI/preamp method is also an option - and much cheaper!
Let us know how you get on.