John:
You should also be able to set it so you can play any RH part from the bottom keyboard. That's what I do with my Tyros/Motif mix. If all the the Motif lead parts are off then I select a Tyros RH voice. Or I turn off the Tyros RH voices and select a Motif Voice. Or I can layer them. All this while the LH plays either a Tyros Style or a Motif Performance. Of course mixing parts from the Style and Performance can also be done but the syncing can be difficult. In any case I play everything from the bottom keyboard ( Motif ).
I know Joe, but that would be a waste of the RH sounds on the lower keyboard. In this thread I started on the assumption that a KMA is an add-on and that you certainly want to miss out on the RH sounds of your main arranger keyboard. Even I do not want to miss out on the RH PA800 sounds.
Deane,
Looking forward to that mate, who knows Donny might have second thoughts !!

Diki,
Not all that many get down tho this, the basic MIDI connection, let alone what you propose. I played around with those combinations many moons ago but let it go for being too complex but most of all too impractical.
Still waiting though for some of your musical postings !

regards,
John