Originally Posted by Pop N Wood

Most people are going to want the larger battery, even with the less capable motor.

Smaller batteries can easily support 1500 watts. Luna used to carry a wolf pup battery, under 2 kilo, 200 watt-hr, but 35 amp current limit. The only limit with that battery supporting a bigger motor is range. One guy says he loved that battery because it gave him two loops of his mountain bike trail per charge.

But none of this changes the fact less capable motors don't have a weight advantage, and ridden at an equivalent power level bigger motors yield the same range on a given battery as less capable ones.

With the possible exception of legalities from a rider's perspective there is no real advantage to the less capable motor that I can see.

While you seem fixated on what defines a bicycle, my conundrum is I feel the only real way to save weight on an ebike is to limit battery capacity. That means limiting use of the motor to achieve any sort of range. At some point why even have an ebike?

One other thing to consider with battery size is life expectancy. All else being equal smaller batteries need to be charged more frequently and have less reserve capacity as they age. Thus they will need to be replaced more frequently.