so 120 input watts is about the size of a 400 watt hps give or take. I understand the math may be fuzzy for this discussion.

Next question: do you change the spectrum around or just stick with 3000k. Do LED's even have a color temperature similar to T5's or HPS? Besides the color what type or size LED is best to consider, or does the 120watt figure pretty much assume a certain LED size? I keep hearing different stuff about 3 watt lED's vs 1 Watt. Just not sure what to look for in the actual LED itself, not that I intend to build it, I just want to make sure whatever fixture I pick has the right LED inside and the right colors.