Friction pads would probably have much more predictable wear (potentially in excess of the expected lifespan of the critter), whereas the discrete, stress-conce

Friction pads would probably have much more predictable wear (potentially in excess of the expected lifespan of the critter), whereas the discrete, stress-concentrating nature of gears would put them at higher risk of a single weak spot leading to cascading failure (then again, they'll still technically last almost a lifetime :)).