I own both instruments (in keyboard format). I think they're the same keybed. If not, they're certainly very close . . . albeit I will say that the P6 keyboard has always felt slightly better to me . . . just seems to be more evenly weighted over the full keyboard. I could be imagining that, or it could just be my particular instrument(s). In any case, they both have excellent feeling keybeds (assuming you like the semi weighted, synth-action feel to begin with), and if there is indeed any difference between them, I'm not sure it would warrant the $400 difference.