Krubbz:
I chose an Arduino for the simplicity of the platform. You won't need to know how to program to run any of this stuff - although the circuit assembly might take a little work. If you're using USB-MIDI you won't need to solder anything (just plug the wires into the Arduino). Is your current setup MIDI-based? I sent out boards for people to test last week so things are moving along.
Also updates:
Implemented VRC6 (for powerpak users) - Both square channels + sawtooth working perfectly
Channel remapping - MIDI channels can now be reassigned on the fly with a controller in P1. They can even overlap! So you can assign a single MIDI channel to multiple channels on the NES and they will play simultaneously. A detune / transpose option was added so you can create multi-channel leads if you are using this as a live instrument.
Video once I make a decent demo song.