As an aside, I dunno what you use for output, but I made an op-amp output board to bypass the noisy on-board output (which goes right past the PPU and picks up a ton of noise) that really improved the cleanliness of the audio. More info as well as the schematic and board layout can be found here. The second iteration, though SMD, can be powered with 9VDC so you can use one power adapter to power it which is nice.
I use low-gains NESmod currently, but after listening to the NESA mod my interest is definitely piqued. Is it only RCA out? or will NESA work with 1/4 outs?
i use a powerpak with my NES and i love it, yes the NES is always the lead in, but it dosent take away from anything (in my opinion).
my drummer wears earbuds and i program the noise channel as a metronome so he can play along in sync. plus if your playing a venue that has good sound and good stage monitors, its almost impossible to get lost, but practice makes perfect.
the dreamland theatre in ypsilanti is usually a safe bet for shows, its a decent venue located downtown.
the the b side is also a great venue in downtown ann arbor that does all ages shows.
other places to look at would be the blind pig, the half ass (i dont know if they still do shows though), the metal frat, those are all located in ann arbor and surrounding area. you almost always get a good turn out if you advertise to students since u of m is right there.