Dude, if you're running CO2, hell.. even if you're not (you can dim), you should seriously consider the Grower's Choice ROI 720E. I posted
*here* about it. I am in the process of revamping my 4x4, and just happened to hang this light at 4" from the floor. For shits and giggs, I decided to PAR test at 48" with my Apogee.... yeah. You'll just have to see.
Also, GrowGeneration created their own fixture that is based on the ROI 720E called the ION 720, and they are having a pre-sale right now. I believe you can get it for $850 or so right now. 2.6 umol/J, 720W true watts (puts out like 1800 PPF), 47" x 47" 8-bar LED fixture with Osram LEDs, dimmable (knob or via an external controller). It's a great fixture for the price, I just liked the spectrum and the sheer awesomeness of the ROI. I almost bought the Gavita 1700e, and I am very glad I didn't. Would have been a waste of money.