Rikki, I still think you should give up on all that hardware stuff and drift back to the comfortable world of software based arranger systems. Oh well, what do I know ... I am just the 800 lb elephant in the room.

I just use Live - Styler for the auto accomapaniment parts. The lead or melody voices I go thru Kontakt or B4, etc. In this regard I keep things very simple and stay away from bank changes, etc. and load up instruments that I will be using on separate channels and switch channels with my controller keyboard....very fast and fail safe!!! Live - Styler works fine on with styles concerning any voice changes that may be required.