The 10.9A would be a good bit less in losses in the 50' #12 extension cord. I calculate 217 W as the loss for the extension cord at 11.5 hours to charge with 0.1588 Ohms for the resistance of the extension cord. So even if the contacts heat a little, I'd bet it isn't more than 300W losses per charge. This little exercise did make me realize that you do pay a penalty for faster charging at 240V, since losses are probably less at 16A than at 32A. If all wire were the same from EVSE to car, losses per hour are 1/4, but charging takes twice as long, so you end up saving half of the losses. With the smaller wire size for the 16A EVSE, there are more losses, but I bet losses are still 25% less for the lower amperage. I'd guess that those using the 12A OEM EVSE at 240V would cut losses to at least half that of charging at 32A.