Don,
I tried using the program change buttons from the DGX300 this morning and it works fine. Because I'm only using the one channel, that's the only function currently being used. If, however, I also had the clock on the MidJay set to clock= on, now I'm able to start the style on the Midjay by pressing accomp. on on the DGX300 and I can stop the style from playing by pressing the stop button on the DGX. Also, if I turn off the accomp. button on the DGX, only the drums play on the Midjay. I'm sure more possibilities are there but this is what I've played with today.

By the way, two of my customers living in the LA area that read the forum came to my store last night and both have ordered MidJays. I think we have a winner here! One of these customers has a PSR3000 but needs faster ways of playing Midifiles with cleaner crossfades from one to another and the Midjay delilvers for him.
George Kaye
Kaye's Music Scene