I put in a heat pump a bit larger than needed to cool the place in the summer, so that it can almost heat the place in the depths of winter.
That was after my 25 year old central air was well and truly pooched, and died .
Gas furnace still makes econoimic sense for most of the winter heating.
But if something other than the fan that both use as an air handler dies in the gas furnace, so the gas get locked off, all it takes us heat wise is a couple of 1500W portable electric heaters run overnight when power rates are cheap in the coldest GTA winter cold snaps , and the heat pump can keep up.
Costs me about $25 a month more in the coldest part of winter to do that.
But it lets me replace any failed furnace with something other than a gun to my head.