Forgive me for offering what amounts to off-topic trivia, but during my BAC111-200 conversion, our flight-controls groundschool instructor - who had worked at BAC - claimed that the roll-rate could equal that of the EE (BAC) Lightning in certain circumstances. As I recall, you needed to have the spoilers slightly extended (i.e., as medium airbrake) to achieve the best roll rate. (The spoilers on the upgoing wing would, of course, then retract.) Whether the speed was the higher the better, and whether that would be IAS or TAS related, I don't know.
Chris