NH has some of the highest electric rates in the USA...I would not consider electric for heat unless I was using solar panels and only needed it occasionally. Plus, I (and this is me personally) just don't like the thought of a WH as a boiler substitute. While you can buy WH with a large enough burner, the average ones aren't big enough for a typical house. Plus, unless you buy a commercial unit (and they have much shorter warrantees), they are designed more for batch operation, not continuous use as you could experience in NH. And, an electric one rarely uses more than 5kW, and that isn't enough to keep a house warm in NH in the winter. Take a week where it barely got above single digits last winter and see how stressed the things would be!
I'd go with the Buderus and put in a propane tank, or make the investment to go solar with a good backup system if you can afford it. they haven't started to tax the use of sunshine (yet!).