That sounds great man. I grew with a 600 in a 3.5x 3.5 for a couple years and it was perfect. The 600watters are just awesome, very effecient. More efficient than the 1000's. The 1000 gives off more lumens, but is quite a bit hotter, and for a 4 x 4, I think the 600 is made for it. Just replace...