Tony...if I may...

I upgraded from S950 to S970.

Biggest differences that matter to me:

Screen size

On board storage

Better sound engine, chip or whatever. Anyway it sure sounds better to my ears.

Editing capabilities

Audio styles

Human voices

If the S970 had sliders and human voice multipads(Do Wop etc)...I'm not sure that I could tell the difference between my S970 and Tyros 4.

And the biggest reason I upgraded...

I sold my S950 to a friend.