I've got the same tank, and am mulling over a similar question (regarding flow) as you are..
For LPS dominate, which mine will be as well, I think 1 MP40es will be fine for now.
If you have time, head over to Long Island Aquarium (rte 231 in Deer Park).. Great store, but more importantly, he has a single MP40es running on his 90 gallon display tank. It'd be a good way to gauge the flow without having to buy anything.