The best I have for you is stop thinking Yamaha. Going from one major keyboard to another requires a clear mind that is not trying to follow the systems of their old keyboard.
My trip form Technics to Roland and Yamaha was not too difficult, but I found Korg to be a different animal. Why is it difficult? Because, in my opinion there are far more options. Korg’s manual is not friendly but it does have your answers.
My need to get the Pa800 ready to use on a job brought many frustrations.
Over 12 years with Technics I should have the OS down pat. After a Psr900, Tyros 2, and a Tyros 3 I had no problem with the OS. My advice to you is to learn one area of you Korg that’s the most important to you then go on to the next.
I do not regret, no better still, I feel real good about Korg, I’m glad I put the time in to understand the keyboard
In My Humble Opinion, John C.