Motor plate on right will work with either sensored motor or sensorless but motor on left the motor will run the wrong direction where the sensorless can do reverse rotation without any changes other than reversing a wire on programming the speedo for reverse rotation. Sensored motors have timing built in so running the wrong rotation makes the timing backwards as well so instead of positive timing you now would have negative and the car wouldn't be fast.
Thanks everyone was just curious. Bought a really nice roller used for nothing but its MM3 with the plate on drivers left so I wasn't sure. My DEST210 is set up traditional with MM3, plate to the right.