The thing I hear is it's not the keyboard it's the keyboardist...well of course a better player sounds better..
BUT....no matter how good you are...you cannot make a poor sounding instrument sound good...so it DOES effect your quality of performance overall.
I am talking about a instrumental song piece...not background for a singer.
and you don't think a Pa4x, SD9, T5, can sound amazing also, I know so for sure......
NEW is not always better,.....that's one thing that has been proven time and time again...