I live in the Dallas area and unfortunately have an air transfer heat (joke) pump. I can assure you that I am NOT happy with it and would never recommend that anyone use one. They might be better that resistance heating in the moderate temperature range but when the temps drop below about 35 degrees they will eat your lunch on cost to run. The colder it gets, the more they run and the less they heat. When the temp drops below about 20-25 degrees, they are lucky to maintain 65 degrees in the house. My thermostat was set at 67 degrees and there were nights when the head pump ran the entire night and couldn't hold the 67 degrees. Result was a $670 electric bill for the month to heat a 2200 sq.ft. house.