Well let's see...since you cannot load , edit, sequence using audio (Wave), on the Yamaha s950...I would say the MS is much more advanced..

The content of the loops is in material...you can use any wave loop...even the few in the s950, if you can ever get them out of the keyboard...

Listening to the Tyros2 demo has no common comparison..ordinary midi seq or style that can easily be beat by any Korg , Roland or Ketron product

BTW: Using audio loops...are way to much trouble...I too rather use PCM samples controlled by midi..