I've been using Arduinos in projects for a few years now, really handy devices! My only complaint is the craptacular DAC/PWM output. I've designed and built dual 10-bit DAC daughterboards for the Mega, if I have to do it again though I'll figure out serial communication to a DAC for waaaaaay simpler build.
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edit: Please excuse the work-in-progress wiring in the above pic.