I agree with Scott,
Tyros 4 for me is just incredible. T3 was good, but 4's voices are much better, drums - wow.
As for playing live, well. The registration button system I have always hated as i'm more of a live player and having everything set up on one button is a no no for me.
I tend to choose voices as im playing, so the multi-page menu's for me are a pain in the "ass".
However, for most who use the registration buttons, yes, this keyboard will be easy to use.

I have to say at this point, i wouldnt trade my T4 in for anything on the market now - NEVER! I love it.