Cory,
Rather than running both pumps as returns, why not use one of them for a Closed Loop and reduce your sump and overflow rates. You will pick up better contact time in your sump and reduce the risk of microbubbles and a loud overflow.
As for the SeaSwirls, we had one on our 75g for a closed loop and it was! Be sure to size you run can handle the flow rate.
-Doug