Not exactly sure what were you aiming at.
Anyway, as you pointed out and which I also understand:
->closer to the rim, bigger efective area, bigger torque, longer the rotor(more magnets on the rim), more rotating weight
->closer to the hub, less torque, shorter rotor, less rotating weight
But I wonder, do motors do better when magnets and coils are moving faster relative to each other. I do know that generators with more magnets&coils generate more voltage per rpm.
