600 is 95000 lumens and the 1000w is 150000. i believe there is a direct correlation between lumens output and heat. get your self an in-line and some air cooled hoods. its the best way to get rid of heat. buy yourself a 600, then when you have the finances, get a second. yes, the 2 400's would work better for coverage, but not for lumen output. figure out what your budget is for a setup, then expand when you crop out. good luck!