A modern heat pump designed for colder regions is reasonably efficient even at -25C, as in being able to output more than half of its maximum heat and still be

A modern heat pump designed for colder regions is reasonably efficient even at -25C, as in being able to output more than half of its maximum heat and still be far enough away from its 1:1 point to make it efficient (compared to resistive heating). So, still very useful as long as that particular output is sufficient to keep your home warm or at least just require a bit of additional heating, and that it's not that cold all the time. Obviously before investing in any type of heat pump one has to consider the nominal temperature range during winter in the area where you live. Even though I'm very happy with the performance of my comparably old heat pump there are definitely regions in my country where it would be less useful.