As far as the metal pump being shallower?
Mine was not. The blades on my metal pump were about 1/16" longer than the plastic ones. They were also thicker and yes, the pump was heavier. This rotational mass could, I suppose, hinder acceleration, but the mass is not huge and is fairly close to the axis of rotation.
Terry, what exactly are you calling the cone?
My impeller exploded in about 10 pieces. The bearings in the pump also felt rough compared to the new pump.
