I have a kn5000 (isn't it about 20 years old now?!)
it does things that were so far ahead of its time, it seems like the newer keyboards are finally catching up.
a couple of examples that come to mind
1) the msp pads actually sync to your tempo (when I played with a tyros 4 I couldn't get it to do that---neither could the salesperson)
2) you can split the keyboard in many places and have different instuments
3) incredibly easy to adjust sounds to your liking (I didn't like the trumpet on it....I made some minor adjustments and I feel it rivals the real thing)
this is as close to a "prosumer" keyboard as you will get.
they didn't hold anything back (keyboard companies now want you to get expansion packs and modules)