I'm with the "Korg cleaner, Yamaha fuller" opinion. The only voice on either that to me was different in a way that I didn't like was the Sax which to my ears sounded significantly nicer on the Yamaha -but this might well be reversed comparing other sax voices.

There is an organ comparison in there but neither blew my socks off, both lacked depth.

As a long term Yamaha user I would get the Genos if I had the opportunity. If I was a Korg user then I don't think there is sufficient difference to justify a change unless you really want to go from the Korg sound to the Yamaha sound.