although the risk of failures in the hub kits is lower than crank motors,.a plug and play system where each functional block can be easily replaced should still be a worthwhile consideration. Such as (in order of decreasing risk): pedal sensor, brake sensors, speed sensor, LCD, controller, motor wheel. When you put for example a controller inside the motor, you actually increase the failure risk of the controller (because of higher ambient temperature) on top of losing the easy replacement feature.