One suggestion: It seems to be the consensus opinion that we need some blue and red, if not green also, in order to get the color rendition we want. Using all cool white will not give the reddish plants, or the red colored fish the appearance they should have. So, you could add some red and blue LEDs to the mix. But, if they are spaced far from the white LEDs you will get colored shadows on the substrate, so it will work best to cluster the reds and blues with whites. You could use 1 watt red and blue LEDs, and make every other white be a very closely spaced cluster of red, white, blue. They wouldn't add any significant PAR, but they might help the color rendition.
I'm in the process of designing and making some LED pendant lights for my tank now, and I plan to use 10 watt cool white, clustered with a red and a blue 1 watt LED. Until I try it I don't know how effective this will be. But, using 10 watt LEDs might work out well for you too - they seem to produce about 800-1000 lumens of light apiece, per the sellers claims. Just something else to play around with in your head.