A lot of what has been discussed about the similarities and differences between the ADV and SDC pumps is over my head but it sounds like the concensus is it's basically the same pump but the SDC is controllable and the ADV is a constant speed. I've been reviewing the pump curves of these pumps as I'm looking for one that can do 350 gph at 15 ft. and it seems the SDC can do that but the ADV can't (model 9.0). Why would that be?