Some random thoughts...

Both boards are superb.

If it's important to you to be able to replace ANY onboard style with ANY that you prefer, Korg lets you do that. Yamaha's are fixed, except for the user section.

Korg's drums can't be beat. (pun intended)-they are in-your-face LIVE.

Korg's controllers allow a great deal of expression once you learn the OS.

Yamaha's woodwinds rule. (The 'sweet soprano sax' - even on the entry level PSRs blows away anything Korg has to offer).

Korg's styles are interesting. The style loops are often longer by a measure or two. Plus when intros are played in a minor key, the Pa800 will sometimes play a totally different intro than when played in a major key.

OS is a major hurdle on Korg, especially if you are accustomed to Yamaha's OS. When I first played a Korg, I turned my nose up at the quality of what I was hearing. One needs to give it time. Now I am amazed at what I get out of the Pa800 - and also very pleased with its roommate - the S910. Two different boards, each with their own set of positives and negatives.