Can a heat pump work in New Jersey?

Looking for some insight on how feasible it is to heat a smallish home (about 1,500 square feet of conditioned space) with a heat pump in New Jersey. Some background: we recently discovered a problem with our natural gas boiler and were trying to decide whether to fix it or replace it with a heat pump. We have a forced-water heating system and no central A/C, so the house has no ductwork, but I figured we could install a a heat pump system with mini-splits. However, so far three contractors (people I contacted through HomeAdvisor specifically for heat pump quotes), have assured us that it's simply impractical to heat with an electric heat pump in this climate. They say that at minimum, we would need to keep the gas boiler as a backup.

This baffles me, because everything I have read up to this point indicates that simply isn't true and hasn't been for several years. Sources like Consumer Reports, the New York Times, and Yale Climate Connections all say heat pumps are effective in temperatures far colder than New Jersey's. So who's wrong--these reliable sources, or these contractors who claim to be speaking from their own experience in this particular region?

Does anyone here live in NJ and use a heat pump as their only or main home heating system? If you do, how has its performance been in cold weather? Does it work well on its own, or do you need to rely on a backup heating system? And how do your heating costs with the heat pump compare with what you used to pay before?

Follow-up question: If these contractors simply don't know what they're talking about, how do I find one who does?

T