The maximum roll rate for many helos is not affected strongly by forward speed as long as stall is not reached. Up to perhaps .6Vne the roll rate should be too high to be a factor in any FTD evaluation. I have experienced 130 degrees per second in several Sikorsky helos. What FTD needs to worry about that?
Do you mean control power - roll rate for 1" of lateral stick? Even so, this is largely unaffected by forward speed.