If the impeller is metal, and it almost certainly has to be, it would have performed far better than those later ones made of Bakelite because the edges would start sharp and stay sharp. If you note the cutaway picture showing the mechanism, this must have used a reversing motor since the structure of the impeller and the pump vanes makes them have to turn in opposite directions to do their tasks. Since the portable fills through the same pipe used to drain the machine, I wonder if the machine was filled with the pump turning in the "WASH" direction which would draw water in making it fill faster than if the water had to negotiate the pump chamber using gravity. If the impeller were turning and throwing water as the machine filled, it would also avoid the problem caused by the rapid expansion of the air in the tank that is encountered when very hot water is suddenly thrown up into the room temperature air over it.
We had a D&M Frigidaire portable that started the cycle with a purge with just the drain pump running, then shut off the pump and started the impeller. Maybe it was because we kept our water heater at 160F, but the dishwasher would throw water out of the steam vent at that point. My father tried holding a folded towel over the steam vent to avoid the splash. That caused the cover to buckle and water squirted out at some area around the gasket. Since the fill flume was located in the steam vent, the watery blow back was made possible. They probably should have taken the water down closer to the bottom of the vent through a tube; then it would not have been blown up by the rush of hot air. Frigidaire Service was out a couple of times trying to fix it, but after they tried watching it fill with the lid open and splattered the kitchen ceiling, it left the house and we bought the first Mobile Maid.
This forcible ejecting of water can happen in KA dws that have the Sani-Rinse where the pump stops while the gallon of water is heated to 180F. If the thermostat allows the water to reach temps higher than that, water can be blown out through the vent under the door when the pump restarts.
By the late 30s, the built-in Conover which later became the Westinghouse model was a front opening, undercounter machine.
I haven't tried it with dishes, yet, so I can't tell how well it washes. 
