Some others have asked for "parenting" or group rotating. I'll have to stew on it a bit to see if I can come up with a super simple interface for that.
Another idea is if I exposed the "smoothing" control. That way you could do hand gestures but have them move at a different speed than the mouth. The mouth-shapes do get "smoothed" so they aren't changing too rapidly, I may be able to make that a control that could be useful.
I'll add both of these to do the research list!