Is the X1 better than the XD9 .... hmmmmmm, that depends on your specific needs. If the piano sound is important to you-XD9, if sampling is important-X1, if multiple outs are important-X1, if aftertopuch-X1, Drum remix-XD9 .... see what I mean? There are things on each side of this coin that will appeal to you.
For me - the XD9 is better suited than the X1, but if buttons and navigation are not something you fool with during a performance, then I'd rather have a VA7 I think. If you need a mic input - then the Ketron is your only option with these two choices.
Everyone, and everything I listen to is my teacher. Every instrument, every voice, every sound in nature ... they are all my private tutor ... 24/7 for free.