It doesn't make much of a temperature difference when you're able to circulate air efficiently. I have fans pushing air inside the veg room, and fans that pull hot air out. Nothing fancy, just a couple of tower fans pointed in opposite directions. But I also have fans inside the room itself that circulate the air, and as mentioned before, one on the ballast. Without these fans, the temperature inside the room would reach 90-100F pretty quick. But with them, the temps never raise above 80F.

Remember, the ballast won't be the primary source of your heat... it's the bulb that you have to worry about. I figured for the all in one system, it would maintain a steady temperature better than an open-hood reflector might, but then again, I've never used one of the all-in-one systems before. Whichever you choose to buy, just make sure that you're able to keep air circulating inside the room, and preferably somehow pulling in air from outside the closet. It doesn't have to be ultra-modern, it just has to be efficient enough to keep things cool.