Regardless of the boiler make may I make a suggestion on the placement of your boiler? I would be thinking to put the unit close to the shop, think of it this way, you will be in your shop more than the house so feeding it will be easier, if you do get interested in somebody other than your old dog, that person will probably appreciate the stove being placed at the shop so they don't get blasted with smoke when they visit or spend the night! Feeding the boiler will be easiest at the shop rather than walking and hauling wood to the halfway point. Emissions, here is a simple trick I use when placing a boiler, cut a sapling about 10 feet long, tie a piece of flagging tape to one end and stick the other end into the ground, the flagging tape will tell you exactly what the smoke will do at that particular spot. You mentioned all models for conventional units, have you given any thought to gassers, I will be installing a HeatMaster G-400 in a couple of weeks to replace my old Wood Doctor, I burn a lot of wood (35 full cord ) per year and want to reduce that usage.