This is super coincidental actually. I've been looking into modding the M1000 for a bit but realized it was a bit out of my league to do from scratch. (Not an 8bit ASM hacker). What I have been working in the mean time since it's more up my alley, is porting your prophet 600 firmware to my Six Trak.
I've made some early progress. I have some debugging questions which I'll shoot over to you in a direct e-mail sometime this week once I have done my own due diligence.