So it looks like the PSR-S910 will have the same amount of these voices as the T2:
Mega
Sweet
Cool
But will have only 25 versus 58 Live! voices. 
And will have only 38 versus 42 S.A. voices
The S910 will have 5 new drum kits. We will find out if any of these are Live! Drum Kits. 
The S910 will have 322 styles versus 400 for T2. Of course, these missing styles are available and will sound better on the S910 than they do on the S900.
This new keyboard will be pretty much as good as a T2. Advantage: onboard speakers, mp3 playback. Disadvantage: some missing live voices and no ability to load samples. 
For those who want those SA2 voices but aren't willing to ante up more than $1600, we will have to wait another two years or so. 
Beakybird
[This message has been edited by Beakybird (edited 07-23-2009).]