[lincpimp]

Both mega and neu make 6+ pole motors. Not sure if they are any better than the 4 pole motors that most use, but I can say that from experience that the 4 pole motors are better than 2 pole motors for heavier vehicles.

No idea if they are more effecient but they should make more torque. As far as using a larger diameter shorter length motor over a smaller diameter longer motor it makes more sense for the large range of rpm that we encounter to use a smaller diameter longer rotor. It will be able to accelerate and decelerate faster than the larger diameter shortor rotor motor.