What kind of corals do you have? for a mixed reef with sps in the middle 24" x 40", you could use 1 32" controllable fixture with 120 degree optics. You would have some shadows that way, if you want complete coverage, I would reccomend 2 value fixtures with 120 degree optics with the long way front to back, or 2 24" controllable fixtures with 90 degree optics, oriented the same way the value fixtures would be.
I just put up one of the 24" fixtures, with the blue channel at 70%, and the white at 40% I am getting 400 PAR in the middle of my tank. The controller is SUPER cool, and I really like the color. It reminds me of old school VHO Actinics.