Hi Danny,
I used to own a Psr 8000, now I have a 9k Pro. I think that Yamaha did a great job in improving sounds and styles, however, I remember trying out the X1 way back when, and was very impressed by the realizm of their guitar strums. I used to be a guitar player so I pay more attention to that.
As I said The Pro is much better than the 8000, but I think the guitar strums in the X1 are still better.
Eric