
Update: I do not want to get into the habit of policing auctions, but as always be careful. The odd thing about this seller is zero feedback with the claim to having an old account with tons of positive feedback. Then why not use the old account with the positive feedback? On the other hand, all of the images for the sellers other auctions seem to have the same lighting, leading one to believe either he took them or he managed to find them somewhere. BTW, if you ever catch images from another location, please comment and I'll update the post.
Title link takes you to shots pulled via
this auction. You can find more info on the Grey Matter add-on on
Dave Benson's DX7 Page.
In short:
The DX7 version gives:
# extra patch memory (with function data for EACH patch)
# optional ROM sounds from GMR, allowing 576 patches in a DX7
# patch mapping
# master contoller functions
# transmission on two midi channels
# stacking of sound (makes it thicker but only 8 note poly)
# ...and more...
The DX7II/FD version {includes all of the above?} and adds:
# 8 voice multi-timbral capability
# a sequencer
# a MIDI monitor
# a simple, "interactive" player mode
Again for more info including the list of individual MIDI enhancements check out
Dave Benson's DX7 Page.