If you do the closed loop in-ground the cost to operate is stupid low. The heat side has a constant 50 to 55 degrees to use (instead of outside air temps the could drop below 30 and stay) and the A/C has the same temp to condense with. The cooling operation is not hindered by 90 + deg days that hinder efficiency. With these operating conditions the unit will live longer than a standard system.
Install cost is high but pay back on energy and longevity of the system is a real plus.
I have a contact with Geothermal installation background. If you're ready, I can make the introduction.