I certainly wouldn't use a Kronos for guitar sounds (although they are good)...the Tyros4 has quite a great selection of SA acoustic and electric, and is hard to beat for real-time performance control, especially whist playing styles.

The Kronos has other things I'd find very useful, especially the Karma engine, and the analog synth emulators.

That's why it, coupled with a Tyros4, would be a dream setup.

Ian