I regularly try this, but have never managed to get it looking smooth. There always seems to be some amount of jerkyness to it. It seems to be very difficult to get the amount of movement from before the keyframe to match up with movements after the keyframe, and so the jerkyness. There's no smooth transition of inertia. I wish that I could access the animation curves directly, as in other animation programs, so that I could smooth out jerky movements.