Yeah, not worth it in most cases, but when things line up, it is the best.

I've built 3 houses and got a bid on ground source heat for each one. I finally pulled the trigger on the 3rd house because we:

1) Moved where it was quite a bit colder, -20F for a week is common. 2) We have enough land to trench only 6'/2m deep to bury the loops instead of drilling like we would have needed to do on the first 2 houses. 3) There was a tax credit on it 4) No equipment exposed outside

Absolutely love it and it will make it difficult to move away when we want to down size b/c we'll pay more in utilities for half the space.

We also have some air-source on an addition I built, I'd use it anywhere that was slightly warmer than where I'm at.