Spend your money on proper insulation and air tightness to your new home and reap the rewards with a smaller heating requirement. I have heard of many horror stories WRT geothermal and believe that the quality of workmanship in installing adequate floor insulation may be the reason it fails in some installations as it ends up heating the ground!
This is the best advice, really, as, the better you build your house, the less sensitive, or critical, your choice of heating system. And, the more expensive/complex it is, the payback time gets much, much longer.
Remember, reducing your monthly fuel bill, but having a bigger mortgage for a more expensive system, may be a false economy......