Haha, IMO strain selection is the hardest part of growing! I also would like to run 600's... was too hot for me when I tried. But I feel like I could fix that by adding an additional intake to each cab. Either way, one of my 600's didn't work (cheap ass $20 bulbs, bought for temp tests) so I just went back to my 400's. I outta just cut out that intake and test it on the working 600w that i have.