I don't see why there would be a problem with firmware as it might only think you're going down hill so you require less amps for the same rpm. One other benefit might be stronger regen but I do wonder if that wouldn't be a problem as it will produce more power per rpm than stock so it might...
Has anyone though of replacing the rotor magnets for stronger ones to increase low rpm torque and potentially increase range?. Now in my short research my understanding is that you loose efficiency at higher rpms but this being a city car might not be a big issue. Any thoughts or did someone try...