LunchBucket pretty much hit it on the head. I bought mine before the Squirt was available, and I can put more flow through it. If you already have the SeaSwirl, I would continue to use it in addition to the OM closed loop. More random flow is always better, IMO.
DR, I would most likely go with the 24's. I dont think you'd have too much light, (I've got almost 700 watts over my 58 gallon, dual 250 HQI's and 190 watts VHO), but I can certainly see how you'd be just fine with the dual 24's over your set up, especially if you're gonna be using the T-5's.
Nick