I think the place you've been mislead may have been from the marketing fluff for your hyper-efficient heat-pump. Those systems have one small flaw, in that they can take a very long time to warm up a house (compared with other methods). So I imagine the salesfolks might feed lines like "no need to turn down the thermostat".

Even with that slight "flaw", ground source heat pumps are probably the very best way to go, when circumstances permit.

Where we live here, people with systems like yours need a back-up heat source for REALLY COLD times. A few days a year, nothing more.

Cheers