I put in a dual fuel heat pump in my Massachusetts house a couple years ago. I'd love to have just a heat pump, but those arctic temperature excursions we get - ironically because of climate change destabilizing the jet stream - combined with our ongoing lack of cheap, sustainable electric generation made me want to keep that gas furnace backup for the worst of the season.
Heat pump means in using my gas furnace about 50% less than I was before the switch. And also, new gas furnace is 96% efficient rather than 80%.