Cohiba8250 wrote:It would be worth spending more on the boiler if it's coal consumption was less.
Once you get into the pricey stoker boilers, the difference in what they burn isn't going to be big enough to even consider. The installation will probably have a lot more impact on how it performs and economy of operation than who made it.
Find an excellent used or re-manufactured boiler, any of those mentioned will work fine, the cheaper the better. Take the money and spend it on a great chimney and plumbing. Even a twenty year old coal boiler is going to have a greater life expectancy then the liquid and gas units coal competes with.