I've got a Felt Ninere with a mid drive motor which not has almost 5,000 miles on it. Not an issue with the motor of any kind at all. More then half the miles are off road - rough travel - pulling a trailer. The controller doesn't shift up and down as cleanly anymore and I haven't been brave enough to take it off and clean it or spend the money to purchase a new one but I see that as a very, very minor issue. This was an expensive bike so for a lot of people, it wouldn't fit into their price range but it serves as my car replacement. As such, I service on regular schedules (I have a local bike shop for that) and keep it well maintained. I don't think you can go wrong with a Bosch.