i've done the hps for the flowering stage, worked well, but the plants had a spurt of growth and i was concerned that my attic was becoming a firehazard. had two grows using just the envirolights now the second yeilding around 5oz per plant when dried, which was better than my old hps set up. I'm only now getting the hang of changing the bulbs at the right time as i found if you do it to early the plant stops growing properly and the buds don't form right. I currently have three mexican sativas on the go, which, following advice from my local hydro shop i left grow to the height i wanted, then switched to the flowering light. The guy assured me that the plant would hardly grow with just the flower lights in. I'm now trying to cope with three plants that have gained over three foot in height since the flower lights went in. Fortunately the heat off the envirolites is only hot enough to singe rather than burn as their growing around the light canopy as i've run out of room to bend them.