I have both a Sz900, and a Pa4x, they are both fantastic keyboards --- depending on your needs/desires. Pa4x, a fantastic machine. If you are playing for people it gives all you need, top shelf. It is like have a large streamline truck to move your stuff.

The Yamaha sx900, is sweeter, clearer, natural, a personality of its own. It is like taking a trip with a beautiful sedan.

It is difficult to appreciate a Pa4x in my small studio room where there is nobody but me.
I may sell my Pa4x, working two different OS systems is a bit challenging at my age.
Yes it’s true, I do walk into the wrong room when looking for something.
John C.