Modularman
First, let me apologize for the late response. I've set it up so I am notified when new reply's are created. Second, thanks for your interests and I wish you the best making your Chaos Matrix.
As for your questions,
MIDI merge:
I got lazy with the MIDI merge issue and ended up buying an old MIDIMan merge box on eBay. You could just as well build your own merger using one of the projects on this site however. The Chaos Matrix will work fine without one, but the buffer synchronization features will not work without the merge.
2 Matrix's:
That's a good question. I do not have 2 Matrix's to test this with, maybe you can test for me.
Try sending a couple of sysex messages to the first unit in the chain, and test whether you get the response from the MIDI out on the second unit.
Request Edit Buffer, you should receive 275 bytes back
F0 10 06 04 04 00 F7
Then send a parameter change, DCO1 Frequency
high:
F0 10 06 06 00 3C F7
low:
F0 10 06 06 00 10 F7
If both synths change OSC1 pitch, then the Chaos Matrix will work editing both in a 2 unit mode (12 voice) without any changes to the firmware.
As for layering two different sounds on top of one another, the Chaos Matrix currently doesn't support this without changes.
Please, keep us up-to-date on your progress.
Regards,
Patrick