I think it's a pretty good sounding recording. The PA1X sounds good, as I would expect, but different from Yamaha.
The main thing is it's a safe bet to play any instrument you're interested in yourself. I've found you can't rely on a lot of recordings and even company demos. There are 2 different keyboards that I thought I just had to have because the company demo sounded so great.
One I tried in person and it didn't sound anywhere as good as the online demo while playing live in arrange mode. The other I liked the online demo so much and had positive comments by other users, who apparently just had a different taste than mine or maybe never really compared it to the others that were out there, anyway, that one I bought. It was the biggest dog I've ever played.
Recoding techniques alone can make a keyboard sound one way or another.
As far as individual instruments, I thought they all sounded pretty good except the clarinet and brass was rather marginal to my ears.
As for the flute, if you heard it in person and compared it to any Yamaha, even a PSR2000, I think you would agree that Yamaha has a much better flute. The Korg flute in person sounds very perculiar. They mix some other sound with it that makes it sound unlike any flute player I ever heard. It just doesn't sound real.
Moral of the story, we gotta try 'em out in person preferably through our own speakers. Trying them through headphones does not work for me. I tried one using quality headphones and speakers and in the end, it's the sound that comes out of the speakers that you and everyone will hear and judge.
Other than that, I am interested in trying the new PA800 because it's supposed to sound better in many ways and being only around 29 pounds as compared to around 50 pounds on the PA1X. An important feature to me anyway