the best place to set a wood burner is in the basement. heat moves up on its own, no pumps, fans or mechanical means of distributing heat is required.
The most efficient way to burn wood is as fast and as hot as possible to ensure complete combustion, choking a stove down to make it run longer is inefficient. Another benefit to efficient burning is no need to clean chimneys.
Needing electricity to burn wood is inferior than not needing electricity, what to do in a power outage, Freeze?
Better to store your winters wood in the basement where the heat from the burner dries the wood even further than can be achieved than storing anywhere outside. Again, the drier the wood the more heat one will get from the same stick of firewood.
Being able to store the heat is best, water or masonry as thermal masses. Slow even release of heat is better than fast uneven release of heat.
the best wood to burn is the driest wood, damp or green wood spends alot of its heat just drying the wood so it can burn, very inefficient.
As far as messes, having an organized setup to store wood, and using very little wood while burning efficiently produces less mess. If the mess is in a basement than its easy to clean once a year in a couple of hours time.
When thinking of burning wood for heat if one uses all these to advantage then one doesn't need as much wood (less work, less cost)
I realize that adding wood heat to existing house may pose limitations.
But if one is designing a home and looking for the best way to heat home with wood as heat source an outdoor wood boiler is a very poor choice.
Everyone that I know that uses one goes thru ALOT more wood than I do, usually about 2-3x as a minimum. Spends more time in he process.