After I went back to the grow room I realized I could probably give you a better answer than before. Here are some pics of my curent op. 8 plants are under the 400w MH and they're only 10 days old, the other 4 are also 10 days old and under the 2 40w fluorescents. First thing to notice is that the MH is only about 16 inchs from the tops of the plants, and there's no burning/wilting/etc. Second is that there is no noticeable difference between either group of plants as far as size or health goes....so if you can, save your money, but if your not concerned about your bill, you're not going to hurt the babies.