I also have the FZ200-got it for the long reach. I also have the X10 (Fuji replaced my original one due to the orb issue) and the XF1 (for slipping in my pocket).
This is just a personal decision , but I prefer the X10 (and preordered the X20). There should be no noticeable difference in IQ as the sensors are the same size-both have good output.
However, I prefer the user interface of the X10 for my style of shooting. The FZ200 is a more recent purchase and has a smaller sensor-should not make much difference if you are not printing super large prints.
Good luck- even basic cameras are so good these days, it is hard to make a wrong decision.