Having just changed to an X6 from a B4, I gave it a maiden run last friday inside.
After driving a B44 4wd, to start with during the night, the whole car felt 'appalling' really because I was trying to drive it off its wheels, like a 4wd!
Once a few laps were down, and calmer throttle thumb, the car was also very consistent. Very flat over jumps, and landed nicely too. As Andy has mentioned, driving the car is more consistent, so helps with your confidence. I felt I was also trying to 'throw' the car into the corners (a la B4), so this really doesnt suit the way the car drives!
Try one first, before handing over your cash though!