Cost is one factor, but if you live in, say, rural North Dakota, you may not be able to afford the risk that your main source of heat breaks down in the middle

Cost is one factor, but if you live in, say, rural North Dakota, you may not be able to afford the risk that your main source of heat breaks down in the middle of a blizzard and you can't get anyone in to service it for several days… or weeks. Don't discount the value of predictable reliability.