My mom is 84, uses a cold temp heat pump in VT. It works very well, and is inexpensive to operate. She has backup propane for the -10ºF nights. While propane is expensive, it is not used often. The propane is used in a wood burning stove "looking" device. So it provides nice radiant heat.
The one downside is that the propane unit has a pilot light. So if the propane runs out, she has to get a refill and relight it. But the up-side is that it is automatic, does not need electrical power and will work when ever the inside temp drops below the setting. That's good for remote Vermont where winter time power outages do happen.
I've spent time there in the winter, it's an epic good combo.
NOTE: As mentioned above, certain modern heat pumps have variable speed compressors and do produce ample heat down to below zero without engaging the power consuming resistance heater.