"Equivalent grinds" between FT and RT, as in, the same valve curtain area at all points of lift, is physically impossible unless both are so mild you would never use them. Even similar average areas will not have the same vacuum, inertia load, and reversion characteristics.
The maximum acceleration and velocity are different, and especially different between roller at low lifts (which has the dangerous side thrust vector) and higher lifts (where the FT is limited by its contact length).