I just bought a brand new iMac running OSX 10.9.1 with a fusion drive and x-plane 10. I have USB flight controls by CH Products (worked fine on X-Plane 9 with my old mac). I can calibrate the usb controllers and see that X-Plane reads the full range of motion continuously in the calibration screen without issue. As soon as I switch back to the simulator to fly, the usb flight controls seem to move the designated airplane control about half-way and then stick. At that point, they can no longer be moved at all by the usb controllers. Any help would be much appreciated.

I have the same setup with 10.9.1 with fusion drive plus CH Products and xplane 10.  I don't have the issues you have.  Can I ask what usb port did you plug your CH into?  Also, there are Usb issues with os 10.9.  Mainly usb sound, but I have seen drops here and there.  This is to be fixed in 10.9.2 (they hope).  The issues do involve the fusion drives and how they work with usb.