I just downloaded the S950 manual (someone has to read them!) and found to my disappointment that the WAV multipads have a VERY significant drawback...
For some ungodly reason, Yamaha have decided that they can only be one-shot pads. In other words, they will not loop. This basically destroys much of their potential.
I was hoping that this feature would somehow make up for the fact that you will never be able to create your own audio loop styles, and will be forced to pay through the nose for any new audio styles (plus, of course, they can't be loaded up on the gig as needed).
For many modern styles based around loop production, fills are not as big a thing, and the groove goes from one loop to another. Right, I thought. Finally an affordable arranger that makes it easy to put four loops up and use them as the primary rhythm... But noooooo! Yamaha couldn't be bothered to add a simple WAV loop parameter!
The more and more I read about these new audio functions, the more I realize that Yamaha have rushed them out the door without really thinking them through. Let's just hope that, by the time they stick them in a Tyros, these absurd limitations have been removed.
Oh, BTW, unless I haven't quite grokked the manual, it also appears you cannot link WAV multipads with MIDI ones.