I can't speak about the 9000pro but I did try a psr9000 for a month and I do have an x1. I sent the 9000 back and am still using and loving the x1. The 9000 left me flat in most areas. I felt after a side by side comparison that the brass and woodwinds on the x1 were much better than the Yamaha. I felt the 9000 had better guitars and great vocal processing. The 9000 has multipads the x1 not. The Yamaha has a slightly better piano. Organs are about the same on both.

The 9000 is a beast to handle.

There are many styles on the x1 that are not in your face. The ballads are an example. Comparing Yamaha ballads to the x1's the x1's are more alive not in your face. The bossa's cha cha s and other latins on the x1 are in your face but wonderful. The x1 does not have a standard Rumba. I don't understand this at all. Thankfully there are people like Fran Carango and others who share other manufactures converted styles with us.

In the end there wasn't a good enough reason for me to change from the x1 to the 9000. Uncle Dave did change, so did Don Mason, (I bought my x1 from him) so did DNJ (Donny). They all had x1s and dumped them for Yamahas.
Don has no regrets selling me his and I have no regrets buying it. Different strokes for different folks. Make sure you try one first before you decide not just an hour in the store but at least a few days.

Good luck,

Tom