The "Natural Voice" Grand Piano sound on the CVP209 uses more sound ROM than the entire amount used for all the sounds on the Tyros combined (Tyros has 96MB). The CVP209 Natural Grand Piano has more than 100MB (reportedly 118MB) of sound ROM just for the piano sound and because of that it sounds quite stunning. The CVP209 also uses two processor boards, one for the "Natural" voices and one for the Sweet, Cool, Live, and GM voices. In fact the second sound board is identical to that of the 9000 Pro.

The CVP209 also has more polyphony than the Tyros and 9000 Pro because of the dedicated processors (254 note polyphony). Unfortunately that polyphony is divided amongst each sound board (126 notes each) so even though you have 254 note polyphony total, its sort of misleading.

Yamaha's dynamic allocation of polyphony has been a major short coming in their instruments for quite some time. The Motif Series, EX5, 9000 Pro, PSR-9000, and even the Tyros really aren't capable of producing the full polyphony without severe dropouts and note stealing. Other manufacturers instruments with the same or less polyphony don't have this problem so clearly its something Yamaha should remedy. For example.. a Technics KN7000 and Roland XV5080 have 128 voices of polyphony that are usable whereas a 9000 Pro or Tyros have about the same amount of polyphony and yet if you approach even two-thirds of their limit, they will have severe dropouts. Even a Technics KN6500 with only 64 note polyphony can handle its dynamic allocation better.

Come on Yamaha, make a keyboard with enough processing power to actually use all the polyphony you claim the instrument to have. How hard can that really be?