I live in Colorado...and even with a space heater my rooms stay around 77ish. So back heat for anything but the hatchling corn rack I'll be building (In a year or two at this rate) would be ineffective. I may try it with the BP hatchling rack I'll make (much sooner), but I'll be sure to have the means to switch to belly heat if it doesn't work out.

Basically, it's all about your room temps, budget (back heat is often much cheaper), and preferences.