I have a Classic Keys which is pretty much a Proteus FX with a different sound set. Losing poly is a big problem on anything that sustains. The best way out on these machines is to do without chorus. If one of your sequence layers is a ROM patch, save it to a RAM location and edit out the chorusing.I'm talking about the chorus in the patch, not in the FX processor. Also if any of your patches uses crossfade, that doubles the note use automatically; try to do without that too unless you're only using one patch at a time or don't care about poly.