Although I have both flapperons and spoilerons programmed into my UCD, I hardly ever use them. The flapperons help tighten up loops and inside waterfalls, and the spoilerons improve elevators and outside waterfalls. But these mixes can get you into trouble in a vertical hover, so I rarely activate them.

So far nothing I've tried has stabilized the UCD in harrier flight.....except full left aileron to keep it rolling.