Jorge explained all that in his book. And there was a post about what he has to say about ho t-5's as well. Please, since you are determined to justify buying the 1000 watt light, just buy it and find out for yourself. 14 threads about it is not going to change the facts. Its a 1000watt furnace, a dinosour, a thing of past generations. Why do you think they are available form the same price as 400watt lights. Let's see, 1000watt furnace, air cool tube, vent fans, duct work, light mover, closets getting kinda full. Oh thats right you have a room. You won't have to worry about heating it. VV