I have ridden over 14,000km /!!!!/ on my EPLUS .
Strange clicking noise from the back had nothing to do with EPLUS motor.
It was quick release not tight enough. My EPLUS fell on the side once, /kickstand sinking into soft soil/
and quick release must hit the rock on the grass.
EPLUS drive can develop 80Nm of torque and quick release must be really tight, beside EPLUS uses very solid very thick torque arm.