Very interesting, but wide, full-span ailerons work fine for me for cancelling engine torque in hover, allowing rolling against the torque. One little trick I have used is to increase the aileron chord in innermost 15 or 20 percent of its length - the portion that is swept by the propwash in hover - to give stronger roll authority against torque, and the increase in servo torque required at high airspeed is only about ten percent. The ailerons should extend almost to the fuselage side, however.