Tech 21 Sans Amp RPM

Before I run out and buy one of these things, does anyone have experiences they would like to share? How good is the Tech 21 RPM for helping produce a clean, clear, natural amplification for acoustic? I read the reviews at Harmony Central and all have to do with bass guitar, heavy metal, grunge, etc. I would like to run an acoustic with pick up through it and also mic various acoustic instruments and voice and run the mic through it into a PA or amp. Thoughts?