From all the research I did when creating the rules and testing we did locally the 13.5 motors are a much better match on our track for 19T so that is what we made our rule at.

The problem isn't the speed so much as the characteristics of the motor and how they affect handling. With a brushed motor when you slow down even slightly there is drag in the motor causing you to slow down quicker effecting the weight transfer from rear to front more then with a BL. With a BL motor when you slow down from full throttle to partial throttle the motor coasts with almost no drag so you get less weight transfer to the front. This cause the car to act like it has more push at speed. Drag brake can be programmed in but it will not kick in until you completely get off the throttle.