I think you've hit the nail on the head Esshup - finding an design and installation company that knows how to properly design and install the system.
Here out west I am mostly interested in a Geo Thermal system to cool down the hot summers (in 2006 we had several instances of 100+ temperatures). To keep a house in the 70s air conditioning would run probably from the middle of June through August almost non stop.
When we build our house up north we wanted to go as green as possible. Solar/wind power, geothermal, etc. Ultimately I don't know how much the budget will support, we'll see when the time comes.
