I don't have an RBI rack, so this is just a more general statement.

My room temps tend to be in the low 70's during the winter. Our homemade racks keep the temps warm enough inside the rack just fine.

However, I bet if I'd had a warmer room temp, I might not have gotten 2 RIs out of 9 snakes when the heat in one of the racks failed. On the other hand, if it had been a case of the t-stat failing and the rack overheating, the cool room temps might have saved the snake's lives.