Firstly, the polyphony issue. Most of the XS's voices, although they may use up to six or more elements, they usually use them in a switching manner, rather than a layer (although there ARE some that layer heavily). Velocity switches, legato switches, pedal and panel switches... Many of them only use one or two elements at a time, no worse than any 128 note arranger. The demos and built in performances seem to be drop-out free, from what I've heard so far (about six hours total in the store).
And secondly, about using loops with SMFs... I have heard at motifator, that the XS's sampler loads up over 10X faster than the ES's. THAT'S got to be a huge improvement for anyone that doesn't want to take hours to load up the entire 512MB of RAM with loops before a gig, or wants to add more loops between songs... If you are using a laptop for your loops, it might make it unnecessary, and integrate the loops into the whole arpeggiator/groove player engine INSIDE the XS...

[This message has been edited by Diki (edited 07-02-2007).]