To heat pump or not to heat pump..

[gtownguy]

that is the question. I live near Memphis, TN and am looking to replace my heating and air system. When I first posted on here for suggestions someone mentioned that I should get a heat pump (w/gas baskup). I have had about 10 contractors out so far and they are split about 50/50 on whether a heat pump is more economical in the long run. With such a hefty investment I want to make sure I get the best system possible (economically and comfort-wise.

Thanks