Ok... had a chance to test the s900 for real last night at our prayer meeting, where I do a lot of improv and playing on the fly with no real preparation. A couple of things that I noticed I DIDN'T like were:
1.) When using a string sound, even when the pedal is down, if I let go of a key the sound fades away. I have to actually be holding the keys to sustain a string sound. My Pa1x I can let go of notes and as long as the pedal is down it will sustain as long as I need.
2.) It requires me to play the keys a lot cleaner than my pa1x. I set the s900 to full keyboard scanning and numerous times over the 1-1/2 hours of playing it misread the chords I was playing and I had to release notes and replay to get the right chords.
Other than that (and no touch screen, of course) I thought it was very nice. LOVED the piano sound.
just my 2 cents.
Jeff