Scott,
unfortunately I never do midi multitrack recordings with the 9000 pro, because they use only the GM or XG banks sounds and not the panel voices, which are much better. I know that the Tyros has addressed this problem and -now that I think of it- the SD1 too uses the internal voices to play midi tracks.
So, the next thing I will do after my breakfast (in a few moments ) is to redo the melody track, like you suggested, then I will maybe redo the trombone track, like Uncle Dave suggested, and the guitar track, like Donny and Chico suggested.....then I'll go to bed.....zzzzzzz.....
What would I do without my musical advisors?
(...I'd have a much easier life!!!)