They are a mystery to most, even in the business. Even the high tech plumbing bunch I work with are evolving with this new stuff. It's strange gear with new problems. A problem can be quite complex and not the type of thing anyone is equipped to service. On the other hand, when they work as designed, there's really nothing to do for service beyond a quick vacuum of filters. That's quite a switch from the typical heating system in New England that can be a mass of aging tubing, valves, tanks, boilers, burners, you name it.

Time will tell what they mean in the big picture.

I went with a simple system; one outdoor unit(the biggest single available in the state of the art inverter efficiency-soon outdated) with a heat output of 34,000 BTU's, and two indoor air handlers; 18k btu down, 9k btu up. The open air design of my house makes a simple system like this doable.

I spent just over 4k for gear through my plumber(his cost-we're close ), installed the units and ran the tubing and wiring, myself. Another 700 had it all connected and tested. A big unknown- life span? This has a 5 year guarantee,....

It's a supplemental system to our pellet stove(we have no central heat and no intention of doing so) but in all but the most severe cold(haven't seen it yet....), the heat pump will do it all. Plus we get AC as well, something I never would have considered this far north, up until the last few years.

Instant 500 Maine rebate(I haven't looked into Fed tax break). Efficiency varies with temp.

When you explain to someone, that putting the equivalent of a 1 dollar of electricity into the outdoor unit, will give you the equivalent of 3 dollars of heat from the indoor unit, many are surprised. Cheaper heat than a pellet stove, even at .15/kwh, that's hard to believe.