I'm too new with Korg to form an opinion on Korg voices....other than acoustic guitar and steel guitar....Yamaha shines there.

I'm guessing I'll figure out how to get what I want for voices on my Korg when I work more with it....my winter project.

In the meantime I'm scrambling learning the Korg OS and performing three times a week with my 4X. At present, Yamaha voices are easier for me to navigate than Korg.

That said, even with only six weeks of live performance with my Korg compared to a few years of live performance with Yamaha....I would still choose my 4X.