How's this light doing for you still? I am just setting up a 4x4 and am being told I have to go 600w light for that size but I felt the same as your post states here and have been looking at this exact light.I have the 465w pro perfect size for a 4x4 and not an over kill on umol/s, I am glad I didn't go with the 600w or I wouldn't have enough space for hang height, I would of had to grow bonsai plants haha. I think that is the main problem with people buying LED's they go over kill on umol/s without running c02. My 465W pro has an efficiency od 2.7umol/j and ppfd of 1256. You only need 600-800 umol/s for phat buds. 1000 if you use c02.