Jon, I have no experience with the others. The two 6080 pumps are about right for my tank, which is the same as yours.
Brad may have something there. If you want a controlled unit, the 6110 produces about 3100gph, {I believe} and can pulse. Perhaps that and one closed loop?
Of course then the 6110 is the same cost as two 6080,s.
Guess it comes down to personal preference. All I can say, is that over the years, I have used darn near everything for current in my tanks, except for the direct drive pumps. Nothing else I have ever used, can hold a candle to my streams or the 6110 streams.
When people come over, {other aquarists}, they are amazed at the current they generate, even the random current that can be achieved. Usually once a day or whenever, I point one of them in another way, which makes a new current completely. Cant do that with closed loops. {well maybe a Seaswirl}
Now for something different. My reef is built low, not the wall thingy. So they make lots of current over the top of the reef. I can also point them towards the front center and they will kick up any sand built up there, so one has to take sandbeds into consideration.
Also my sps are pretty young and have yet to grow into monsters like Brad and others have.
So I dont know how the current will change, when this happens. As its more current than my other methods, I assume all will be fine.
The current from them is totally different than from closed loops. Because of the pumps build, the current spreads out into a wide stream, which is more gentle on the corals yet, sufficient. Now imagine one pump on each end, doing this.
Also because of the large cage, they are safe for snails and the such, climbing on them. During feeding, spirolina or clip algae gets on the intake cage and a night, its a picnic area for shrimps and snails.
Of course, as I mentioned before, they have the look like large Hagen powerheads in the tank, so you have to be ok with that. My friends call them my outboard boat motors and if you lift one up to waters surface, it sounds exactly like a small outboard, tilted up behind the boat. Same prop chopping the water sound.
During normal operation, they are completely silent and use little power.