Last summer, I modified my Polysix to have a new "Poly-Unison" mode to simulate the richer dual-oscillator sound of the more expensive polysynths that came before the Polysix. I finally got around to recording a demo and writing a few notes about the mod. If you're interested, check it out at:
http://synthhacker.blogspot.com/2014/01/polysix-poly-unison-mode.html
Chip