very interesting thread!
i make music on amiga since 1994. i've started with protarcker (4ch, 8bit), later with prot.'s sceneversion, melontracker.
then i've got an a1200 and digibooster pro has came with real multichannel capatibilities. with a 68030/50 i was able to play and edit 8-10 channels in 14 bit modes, then 12-14 chs. with my later 68040/40. then i've bought a VSS soundcard with built in mp3 decoder, 24 bit sound - man, that was awesome after paula's fake-14bit modes... full 16 bit replay with 16-20 channels (well, 20 channel was a bit much for the 68040...).
you can hear some of my music made on the amiga1200 and VSS here:
http://pollen-records.uw.hu/tizev.html. point your browser to the "letoltes" link below the cover. 80% of this album has made on amiga.
im sure that for musicians the more channels are the better.
if you want to use some effects (digibooster pro has some basic dsp echo and delay effects fe.) in your song, a 060 surely not enuff for sw mixing 16< channels.... use as much hw channels as you can!
make it ahi compatible for digibooster and for the other audio softwares using ahi. maybe add a nice dsp for real time effects:) panning is important i guess, i know you can do it with 2 channels with volume, but still...
anyway, this project is great, too bad it's not 1998/99 anymore.....

keep up the good work!