IME the VK112 makes a great acoustic amp, lots of clean headroom for most purposes and with Bright ON, very very sparkly. This is based on my experience using a piezo bridge pickup on my AE; I haven't tried it with a magnetic pickup on an acoustic. IMO if you're really after a good acoustic tone you should get a body transducer or under saddle setup; the further away from a microphone (and the more toward an electric guitar) you go, the less of the top's resonance you will hear.
Here's a decent reference http://www.acousticguitar.com/article/d ... ntable=yes
'65 and '03 SG Specials, '12 LP Jr DC, '60s Dano/Silvertone, Dean Fake Korina Vee, Ibanez Frankenstrat, Epi EB-0 bass,
Classic 20 w/6V6 mod, much modded VK112, Bandit 112 Solo, Transtube Envoy II, '61 Reverberocket