@becasunshine , the size 30 boxes and the princess are very very close together in the BK lineup. I wanted a princess, the wife insisted on either an Ashford - or shop other manufacturers. So we got an ashford.
I have no real regrets. In challenging cold conditions i am confident i could run the princess at max output for a few weeks every season, and spend more of thrle shoulders in 24 instead of 12 hour reload mode.
With just the wife and i home we consume right at 11 kwh daily of electrical average, month in and month out. Thats like running a 1500 watt hair dryer about 8 hours every day, and using no other elctricity for lighting, refrigeration or charging devices. And that same 11kwh daily is about the difference between the ashford and princess.
There is no doubt, as above, in low burn modes the combustor and convection deck are where the heat is coming from.
Also as above, at high throttle settings everythig heats up, the wood in the box, the box and the combustor.
So at low burn the wood can burn very slowly and the smoke keeping the combustor fed and warm is enough to heat a lot of homes a lot of the time.
At high tstat settings you get all the same heat out of your big hot fire as you would with any other technology, with the added benefit of the combustor getting raging hot burning up smoke particles that would other wise be wasted.
The heat from the combustor, the combustor exhaust, crashes into a steel curtain welded to the top of the firebox 3 or 4 inches from the back face of the combustor. That curtain conducts heat to the the top of the firebox, where the deck fans can strip it off and blow it out into the room. It's beautiful.