I've had both and I didn't really like the UCD(w/91fx). I spent allot of time setting it up, trying different mixes and CG but it never really performed 3D that well. Wouldn't flat spin, harrier or elevator (major wing rock) or tumble at all. It would kind of do a blender. I sold it at a local swap meet and bought the Flip(w/YS63). Waterfalls, flat spins, blenders and harriers no problem. If I crash it I will buy another one.

Just my opinion. I know allot of people are happy with the UCD.