You really can't take a PSR3000 or a PSRs-910 which are middle of the line and then think you can compare your KN7000 to it and then decide you don't want a Tyros 4 because of the sound.
I mean think about it, you can buy those PSR's for less than the KN7000's original wholesale, which was $2400 BTW.
The PSR's never ever sound anywhere near a Tyros. Some sounds are close but but many sounds are not on both or have a major difference in sound.
I have not heard the S910 live but from what I've heard it's a major upgrade in sound in the PSR line, but it doesn't sound like the Tyros 4!!!
That's like saying I'm going to decide if I'm going to buy a Chrysler 300 by test driving a Dodge Neon and compare it with my old Cadillac.