The technology around now is pretty good, although the better stuff is really expensive.
The big problem you'll have is with installers. We put a new system in (not geothermal though) and it was a pain in the backside. A lot of hacks, scammers, part swappers and sleaze bags. And those were the guys leftover after I scrounged for recommendations, eliminated people with iffy BBB ratings and did a bunch of research.
I guess the good news is that some of the higher end systems, with the right control/thermostat (which these guys seem to want to fight tooth and nail to avoid installing) tell you about problems well before they cause problems. Mine uses a 4 wire serial bus communications net between the outside unit, the inside unit and the control panel and can detect refrigerant leaks, intermittent operation problems, increasing static pressure and temp levels at various points in the system like both coils.
The next controller up from what we got has a pager system built in and can call you and the maintenance company if it detects a problem.