I really must say that in this Michael Voncken video the grand piano sounds much better than I thought. It has more depth and a more wooden sound than what I think I heard in other demos, especially Tyros 4 ones. I suspect it is the CFIII waveform of the CP1 piano, but obviously in a bigger version (longer samples) compared to the version available for the Motif/MoXF, at least that's my spontaneous impression from the video.