I was playing the AC-3 Acoustic Simulator at Guitar Center, and i absolutely loved it. The tone and warmth you get from the modeling is just phenomenal. However, i have to believe that the amp they were running all of the pedals through was some sort of tube amplifier (i cant be sure, it was housed in a casing) I would just like to know, how would this sound through a modeling type amp. Would it just the crap sound crappier? Either way, id have to say in the future it could be a wise investment.
A piezo system would be a lot more acoustic sounding if you could get one of those put on your guitar (my guitar teacher cheaps out by taping an acoustic pickup to his strat, that should do the job ) but it should do good, from what I get from guitar shops I always get put on a crap amp, if it's the same there then the pedal would be wise, get some opinions on it then decide.
To be honest an acoustic simulator will sound just as good, if not slightly better, through a solid-state amp. Valves tend to add a lot of warmth and reduce the high-end sparkle - which sounds better for electrics, but makes acoustic tones sound less lifelike. In fact most dedicated acoustic amps are SS.
So yeah it'll sound fine through a modelling amp, but be sure to find the cleanest, most plain sound available (a Fender amp model would work well).
I hear PA systems are a lot better for acoustics than acoustic amps, apparently acoustic amps feedback too much, so yeah I'd say acoustic's would be solidstate. But keep in mind this is an electric guitar with an acoustic model so it'd probably sound better valve.