I'd consider going with 2 mag7 pumps or something of that capacity and running 1 SCWD as a closed loop and one on the sump return. That will give you 4 outlets, a ton of random current(as both SCWDs will switch at slightly different rates) and a really clean looking tank. Also having two of the same pump will mean that if your sump return one ever fails you can switch in the one from the closed loop untill you pick up a replacement.
I have a SCWD running on a mag 7 and it switches every 6 seconds or so FYI.
Good luck
Evan.