High SEER minisplit heat pumps have finally caught the attention of high efficiency homebuilders. Postgreen, a redeveloper in Philadelphia, touts "geothermal efficiency at a fraction of the cost": http://www.postgreenhomes.com/models/
When you add PV solar to a house and a high efficiency and lo-temp-capable heat pump, then you really don't need to pipe natural gas to the home. (Cooking meals with gas may be preferred by chefs, but it is neither healthy nor energy efficient. Gas ranges put out a lot of CO). That saves the $12/month gas hookup fee.
Besides, you can't send natural gas back to the utility like PV solar does. In superinsulated homes, this scenario also makes solar thermal obsolete for heating and domestic hot water (DHW)
Why? Because even at a solar conversion efficiency of only 10%, in the summer, you are putting energy back on the grid and dollars in your pocket Every. Single. Day. Thus, the yearly system efficiency and ROI is better than solar thermal.
It's becoming accepted worldwide that the only way to acheive true net zero energy is with an all-electric house and PV. Minisplits are part of the puzzle.
A few more of benefits of these heat pumps:
1. Less floor space used inside the house for mechanicals.
2. Compression-cycle air conditioning included "for free".
3. Better zoning is possible than with any sort of central forced air system.
4. In smaller homes, the installed cost is a fraction of a centrally ducted system.