Although layout wiring for RailPro is the same as DCC, that is where the similarity ends. Railpro does not send commands to the locomotive through the track like DCC does, so frequency is not an issue for RailPro. Commands from the handheld controller are sent to the locomotive module via radio frequency, voltage on the track is for power only. Start speeds are adjustable on the controller as well as momentum. A low speed enhance function can be selected on the controller.
Smooth starts are not a problem for me, I run some stock 30 year old Atlas/Roco that give me smooth starts, if not, it is always the locomotive that is at fault, not Railpro.
Maybe other users can elaborate more on your question.
Mel