wow...900 each for those lights and they run PC lighting? Why not LEDs? Or at least t5ho's?
For 1800 you could build the ultimate fixture, or buy one of the prebuilt fixtures out on the market.
For like 200 bucks less you could have this
3 fixtures, full controllability, sunrise/sunset, cloud cover.
Sure that's a reef fixture with a lot of blue but that's just an example. For the kind of money you plan to spend you could have an LED fixture that'll blow the MH/PC fixture out of the water.
They draw so much less power than MH/PC, you'll be running almost 1000 watts of lighting over your tank w/ the fixture you're planning to use, each module in that fixture I linked pulls 60w.
And since they don't put off so much heat, you won't have to run your chiller as much, meaning your electricity bill will be even lower.
I know it's your decision to make in the end but I hope I provided you with a little bit of info on what else is out there!