The AC pumps controls the GPH by controlling the ouput, mechanic, while the DC pumps control the GPH by reducing the speed of the impellers. So the AC pumps consume more power, back flow effect, when adjusted to lower GPH while the DC pumps consume less power when adjusted to lower GPH. Logically speaking, the AC pumps use more power and therefore, have shorter lives if used at lower than max GPH. DC pumps on the other hand last longer and use less power it run at lower than max GPH
DC pump is a lot better IMO.
Would be nice to see the ratio of power consumption versus speed.