Thing I noticed was the regen with a 500D seemed to be less than with (I think) a 350 kit. Didn't even need to use any brakes on an extremely steep hill with the 350 bike (actually slowed me down too much). FOR ME, if it were my bike I wouldn't use this feature at all because I don't like the stress on the axle/dropout even though I know it can be minimized with torque arms.