I believe SA voices are more to be used for solo leads...

for OMB performers who sing the lead instead of play them using a guitar or sax voice wouldn't really require the SA voices.

to be honest when you are using an arranger keyboard in a live situation and you are singing, mostly you are just changing sustained chords and playing a few fill ins to compliment your voice. thats why solo voices aren't always essential... IMO

thats just why i think some people might not care about the fact that the S900 has SA voices...

Nick