My tent would not likely have room for 2 lights unfortunately. I think you guys are right in that I should just invest in a few more CFL's to put around some dark areas or just emphasize the tops more.If you are replacing your 400 w a 600 I'd say instead just go for the 1000 or run both 400 and a 600. But like someone said the extra 200 watts could be easily supplemented with a few cfl and you could customize your spectrum that way.