I like that you can pick the height. At 18" I don't get the best reach from my 50W RHP in my vision cages, which forces me to add a little UTH. The crevices in vision are also annoying. I dislike that racks are always about 6" tall, as my bp lift their heads at least that when swallowing rats. If you're using UTH, I don't know how much it matters, but it probably depends on the ambient air of your room.