What are the differences in the sportsman 2 and the pro seies 2 ? I'm fixin to buy one of these to mount on a 20 ft bass boat and trying to make up my mind as to which one I need ? I know they'll both pretty much do the same thing and I can look at the pro seies and it looks a little better but is it built any better ? Are the pumps the same ? I've read where some are faster and some pumps are louder , is that true ?