I take it you guys are using the USB side of these controllers?
My pro keystation 88 is on midi
there's not a lot of gear that uses the USB port successfully
that and a good midi interface (AMT8) is workable
still is less tight than the serial port on my old mac with a unitor 8 mk1
and also less tight than the Atari I got to work on a few times
so... get a good midi interface that works with the steinberg software
I heard some good things about the midex 8
good luck
