Gas is up these days, but it is still very reliable which should even out the costs in the long run. Also, pay the extra coin for a scroll compressor and a proper "finned" condenser on the AC side. You'll get a better warranty (probably a 10 yr)) and better durability and efficiency. Even if you go with a recipricating compressor, stay away from the tensil condensers. Also, like speakers (Bose sucks), advertising does not equal quality so look at the components rather than the sticker the company stuck on the housing..
With the gas pack, if you and your wife both work, you can do major setbacks of the thermostats during the day (like 58 or 60) and at night...something you can't do very well with heatpumps during the cold months sice they blow such a low temp (unless the headstrips kick in). Also, with a split unit, it's easier to replace in parts. If you've got the original Trane-peice-o-crap your house came with and the compressor goes out, you can go out and buy a new condenser and scroll compressor and you've got a decent unit since the squirell cage in the attic and the furnace will probably last twice as long (or longer) than the compressor and condenser.
