You are correct, Kabinopus. The last one I was using for a controller (on my demo S910) was the P-95, which worked very well.

I haven't even tried a P-105, but I have played the P-155, which is also very nice (and has midi in/out), but also more expensive.

I suppose the best combo would be as Diki said above...a P-105 (or P-35) with the innards of an S750.

That being said, I really prefer my own arranger to have a lighter action, the FSX (semi-weighted) on my Tyros4 being perfect for both piano sounds and other voices like guitars, strings, winds and organs etc..

Ian