Wow Don,
This is very enlightening. I've always ignored controllers that had 'USB' in their description. When I did look at them, most were powered through the USB port, so I never considered using one with an arranger module. This particular controller (Edirol) would be perfect if it had aftertouch.
You mentioned that you could split the board - I assume you control the styles bass/chord changes from the left split Edirol. With a midi in port, do you think it would be possible to control the bass/chord changes of the module with an external device and lead line with the board - through the Edirol?
Ciao,
Jerry