Here's two videos of a friend of mine playing his brand new Roland FP4:

http://www.youtube.com/watch?v=Jb1NRgxjq8U

http://www.youtube.com/watch?v=zOipEW8zUDs

I describe the sound of the "Superior Grand", used in RD-700SX, FP7 and FP4, as a "Steinway sound", a piano timber that is fundimenetaly dark in tone but at the same time has very noticeable bright resonant overtones.