Belly or back heat, flexwatt or cables, it will all do the same thing. Difference is ambient room temps will affect how often the heat in your racks cycle. My snake building keeps an ambient temp of 82 degrees. This ensures the heat in my racks dont have to cycle as often as it does in lower ambient temps. I can bring it higher but i dont like working in a sweat box. My freedom breeder and vision racks have belly heat and my melamine racks have back heat. All the tubs stay 90 hot side and about 85 cool side depending on tubs. Hope this helps