Wow, cool that you got sysex to work on the MC909 - I have a MC505 I've tried to program sysex for but Roland MIDI structure is a bit more difficult! I was able to configure sysex commands for the AN200 easily!
Do you have any examples of which parameters on the MC909 you controlled via sysex?
Yeah REALLY wanna figure out this sequencer trick for the AN200 though. Would be a dream.