Just off the top of my heard, the biggest difference, for me, is that the S910 is using the new guitar mode in the styles, as also featured on the Tyros3.

Any new styles will be using this format.

The physical differences are obvious, the S910 being lighter, with built in speakers, and also using the new screen as featured on the T3.

T2's key-bed has after-touch, the keys are semi-weighted, one more pedal input, three voice layering on the RH.

The S910 will play all the Tyros2's styles without conversion...it will also play the Tyros3 styles with a few tweaks...the T2 won't even load them in.

I like the S910 for it's compactness and the convenience of the built in speakers...I don't need 3 voice layering in the RH...two is fine for my needs.

The S910 will play MP3 files.

I'm sure there will be other comments, so I'll leave it at that.

Ian