Jadnashua
Retired Defense Industry Engineer xxx
A 1.5-2.5 ton inverter-drive ductless air source heat pump (mini-split) appropriately sized for the heating load would pay for itself in under 5 heating seasons even with nickel electricity (and that's at the full installed price of the heat pump not some delta between an electric boiler installation and a mini-split.) Going with an electric boiler and NOT a mini-split would only make sense if you were willing to pay for the extra comfort-cush of a radiant floor or something. A heat pump with some cheap resistance electric backup for the sub-zero peak loads makes more sense otherwise. It would have have half (or less) the operating cost of an electric boiler during mid-winter, and less than 1/3 the operating cost during the spring & fall. In a ~7000 heating degree day climate those are significant savings.
What I suggested back on page one...the advantage is not only cost, but for those few occasions (maybe more?) when the humidity levels get to you, you'd have a/c available, too.