The rear wheels maintain their spinning momentum, when throttle is applied, less energy is required to bring all 4 wheels up to speed
I don't agree with this. When coasting, the rear wheels are rotating at the same rate they would have been without the one way, since the rate of rotation is dependent on the velocity of the car when the wheels are touching the ground (since it's just coasting and not wheelspinning/skidding). There should be no difference in momentum.