It's well-documented that adding thermal mass to a woodstove will improve efficiency.
You can burn smaller splits of wood hotter, causing more complete combustion. The additional heat output won't over-heat the room, because it is buffered by the thermal mass. The thermal mass can keep the space warm long after the fire has gone out.
Many woodstove users will fill the firebox with wood in the evening, and then close the damper, leaving the wood to smolder overnight. This can keep the home warm for a long time, but it is wasteful of fuel, pollutes the air, and deposits creosote in the chimney. This practice becomes unnecessary with sufficient thermal mass.
High thermal mass designs I have seen require a dedicated footing in the ground. This is a significant additional expense and inconvenience vs. a conventional woodstove, which can rest on a conventional framed wooden floor.
How can I use thermal mass to increase woodstove efficiency without overloading the floor?