The weight of the burr wont make much difference to the load on the motor, Niche’s would probably spin up Robur burrs without any problems. It’s just an inertial load until the motor reaches it’s designed speed.;) Not that I would try it.
The grinding rate is set by the burr design for some rotational speed. Faster it turns the higher the grinding rate. These are generic Kony burrs, probably the stainless ones.
Not sure if the image upload has worked.
The inner has a sloped cut. That is working against a straight edge initially and then a sloped cut in the opposite direction. This forces broken beans down through the burrs due to burr rotation. It’s similar to a screw. The slopes in the teeth mostly set the rate. Unlike flat they tend to self feed. Centrifugal force breaks the beans up on flats and forces them into grinding areas.