Xpantastic!

>  > On the other hand, a simple general hardware editor would do fine, I,
>  > for example, don't

Well, not sure about that. There was one for the Matrix 1000 years
ago, and it cost more than the synth.
A decent hardware based editor is likely to cost $600 or more, because
tooling costs will be high, and the number of units sold will probably
be very low.

I have a C structure definition of the Xpander/M12 patch format somewhere.
I don't know how accurate it is, but it's probably close enough to
figure the rest out.