I just test-rode an e-mountain bike in the staging area at an enduro mtb race recently. They're seriously fast and in a fatty's meathooks could cause some serious injury on steep narrow singletrack if hams start buying them and taking them where they have no business. That kind of fatty mass can't react fast enough to float out in time on clipless or even step off and bail on platform. Then there's the problem of brake fade / overheated rotors with that kind of weight if they're able to get on the steep stuff with motor assist.