I use two of the Eheim Compact 2000 pumps in my main system, and they are great. They're quiet and low wattage.
I'm guessing that your sump isn't baffled?
I've just picked up one of these skimmers as well, so I can't comment on it yet. I have read that there can be issues with microbubbles, so I would try to position it in a way where the return pump won't pick up too many of the microbubbles. That may be tough, and it might require some fiddling.
I have run mine in a vinegar/water solution to get it all cleaned out. There weren't any microbubbles, but a run in saltwater may change that.