with a building of your size, I would tend towards both the boiler system using a "food grade" glycol radiant floor heat for the lower level and a small wood stove on the second level. Depending on how much available wood you may have on your property of course! A boiler system doesn't so much care about the quality of wood you burn, my father built his own outdoor boiler and for over 25 years he burned literally everything from old skids to stumps, and or anything else he could drag out of the bush. Where we are, it can get as cold as -40 deg. C in Jan/Feb. (I remember one year it was -47Deg.C "with NO wind chill factor!" ) so your application may not require such a robust system!
He heated the shop (1600 sqr feet), the barn (1000 sqr feet), and his home (3000 sqr feet) all with one boiler system! They also had a small wood stove on the second level of their home and a high efficiency propane furnace for when they were away and could not attend to the fires.
He was at one time planning to augment the boiler with a propane system in the shop in effort to prevent the entire system from dropping to far in temperature when they were away, he built a 10'x10' metal addition on the shop, spray foamed the interior and had a small "botched" or reverse engineered propane furnace he planned to adapt to the glycol grid, never happened lol!
The stove I bought is one of the larger stoves on the market (520 lbs.), it will take a 22" piece of wood and the fire box is 4.5 cu ft. , so about 90lbs wood load, it has a rating of about 86% efficiency.
We owned a pellet stove years ago and I have to say, "what a huge pain in the ass!", not sure if the systems are still as bad but I'm tellin ya, I wanted to blow this stupid thing up! 3 years, then I got rid of it! they may not be as bad these days but I had everything from constant auger jams to combustion chamber malfunctions! and for what you pay for pellets you don't really get a good heat from them, not like a wood stove anyways, not much in the way of radiant heat.