I have the new Yamaha PF1000 in my store and I've investigated Yamaha's "natural" voices with people at Yamaha. "Natural"voices is it's own chip inside the clavinova or PF1000. Polyphony is it's own 64 voices and the sample process is a combination of three different types: Stereo sampling, sustain sampling, and note off sampling. Yamaha has "natural" sounds in the catagories of Piano and Keyboard but not in Guitars, Brass, etc. In the Clavinova products, 32 voices or 64 voice polyphony is for the styles and 64 polypony is for the Panel and Natural sounds. In the PSR9000, 9000pro, TYROS, the polyphony is totally dynamicaly allocated so you can use all sounds for all the keyboard parts. I just went over this with a friend at Yamaha the other day. I hope I am explaining this ok.
George Kaye
Kaye's Music Scene
Reseda, California