Final followup on this topic:

I have been in contact with Mark Anderson, Assistant Manager PKB Marketing, Yamaha America for the past few weeks. After getting some attention on the Motifator.com board with my problem with the PLG150-DR and the 9000 Pro, Mark took some time to follow up with me. First he apologized for the response from Yamaha Support regarding setting midi channels "scaring and confusing" 9000 Pro owners and reiterated that the 9000 Pro was considered a PRO board. He also said that they would take my advice to create a spec sheet for all expansion boards in the future that specified how the expansion boards work (or not) with each keyboard they can be mounted in. If the PLG150-DR continued in production and manual reprints were ordered, my suggestion will be included.

After a few weeks Mark finally got a response from the head engineer at Yamaha Japan who worked with the 9000 Pro: basically the PLG150-DR will never work with the arranger styles, however they thought it might work with midi files and they suggested that I place a System Exclusive message in the front of each of my midi files to set the PLG150-DR to midi channel 10, to wit:

XG Parameter Change: F0 43 10 4C hh mm ll dd F7
hh: 70 (Plug-In Board Part Assign)
mm: 05 (PLG150-DR)
ll: 00 (Serial number) *1
dd: 09 (Track10)

(All numbers are hexa decimal.)

*1 If two PLG150-DR boards are installed, 00 means choosing the first
board
and 01 means the second board.

I'm posting this here in case anyone else is interested in trying it, however it does not work, at least as far as I can tell. I tried several different sequencer programs, variation of the SysEx message and MIDI settings on the 9000 Pro to allow it to accept SysEx messages and never got it to work. As I told Mark, it looks like a good idea that noone at Yamaha actually tried. Besides that, I didn't relish the idea of modifying hundreds of my midi files anyway. Mark offered to exchange my DR board for another board or Yamaha product of equal value but I have declined.

The end of this story is that I'm no longer interested in getting the PLG150-DR to work with my 9000 Pro. It may find use in a future keyboard or I'll sell it. At least I was able to take my complaints higher up the food chain in Yamaha than I ever expected and was able to express several frustrations that I had with the instrument besides the expansion board limitations, such as their disregard for the OPT voice editing panels we'd been promised (it turned out that a third-party in Germany where the 9000 Pro is more popular had proposed creating the voice editors then dropped the idea). I've been told that my concerns were spread throughout all the departments involved, for whatever gratification that was worth.