Heatpump vs. Propane Furnace Education?

Question:Here in Tennessee we generally have mild winters. With electricity at $24.94 per Mbtu (resistance heat) and propane at $28.84 per Mbtu, I am thinking about installing a heat pump. Propane is expected to rise this winter,too. I have not kept up with the advances in heatpumps over the last decade or so. People tell me I want a "scroll" compressor. I don't know what that is. Anyone that feels like typing is welcome to educate me. We are heating ~1740 ft2, R25 walls R35+attic. Thanks.

Answers:
You can find a good explanation of scroll compressors at Wikipedia.

I do think a heat pump is the way to go. Typically they have efficiency factors of around 3, so your electricity should cost 8 to 9 dollars per Mbtu.

A caveat might be if your electric supply is not reliable

I considered a ground source heat pump system. However it would have to utilize vertical wells, and my county charges $240 per well.