Maybe its a dumb question, but I really don't know...
Taking out the hassle factor, is it a) economically and b) environmentally better to heat water and rads off back boiler attached to open fire (mixture of briquettes/smokeless coal/logs) or with OFCH?
I would think that it is more economical and environmentally better to use an oil burner, condensing would be even better. A modern boiler would be a lot more efficeint than an open fire. A stove may be a different matter. I really think you can't take out the hassle factor because it really is a hassleI.E lots of cleaning, no option for automatic start etc.
Your best bet would be to have both so they can compliment each other.