Not trying to start a subjective debate here, just looking for some objective statistics.
I get that high-efficiency boilers are much more efficient, and will save big bucks over their lifetime in terms of fuel saved. I get that they're more complicated and cost more. (I get that the manufacturers can also charge more based on the expected fuel savings.)
But everybody I know who has one is paying through the nose for maintenance. It seems (perhaps this is a biased opinion) that the things are always breaking down, and when they do the replacement parts are always (a) hideously expensive and (b) on backorder.
Is there any data on this? I'm curious if anyone has done any studies on the total cost of ownership of a high-efficiency boiler, factoring in not only the initial cost and the fuel saved, but also a realistic assessment of the actual maintenance costs.