I think the claim to the advantage of an open reflector is that the light energy does not get reduced after passing through a glass lens. This is true for all company's except one. Here is where cheaper is not better. Glass has iron in it by nature, any traditional lens will only allow about 86 % transmission. I am using a reflector that is 36"x42" and has a low iron lens that allows 95% transmission. Air cooling your lights does a few things for you, it reduces the ambient heat in the room which means running an AC less often but more importantly with this size reflector I can cover a 48"x48" foot print at 10" off the top of the canopy with no burn. The closer the light source the bigger the yields, hands down.