Having read through this entire fascinating thread, I thought I'd put in my 2 cents' worth. I have never even seen a RMH, much less used one, but since I first heard of them on Permies, I have read everything connected with them and watched every video I could find on them. And yes, someday I want one for my house, plus one for the greenhouse of my dreams.
I have, however, used wood stoves for my primary heat source, for more than 40 years now, most of them in the same house. When I first moved in here, in 1976, I found a fireplace. One of the first projects I undertook was to take a sledgehammer and a crowbar to it, and rip the damn thing out. My buddy and I put in a brick hearth that consisted of a brick pad over the floor and a brick wall with a hole leading to the chimney, for the pipe.
I put in a Tempwood downdraft wood stove. Anybody remember those? They built them in VT of NH, I forget which. They were welded steel, double steel bottoms, bottom and sides lined with firebrick, absolutely airtight, with a round lid in the center of the stove top, and two variable downdraft ports flanking it. These stoves would be totally illegal today, even though the secondary combustion provided by the downdraft effect makes for a far cleaner burn than the conventional "bottom-up" design.
The Tempwood served me well for 11 years. Then I got married. My (now thankfully former) wife demanded a "legal" stove, fearing that our insurance might be canceled. So for $3,500 installed, in came a brand new Vermont Castings "Defiant" model, their top of the line stove, with a catalyst. That made her happy. Still, we went through 3-4 cords of wood in a winter.
Ten years later, she was gone, and once she was, out went the Defiant. I took a sledgehammer and a crowbar to it, too, and hauled if off to the dump. It was a piece of sh*t. It leaked air, and all the gaskets in the world, and all the gasket cement in the world, couldn't fix it. The verdammte catalysts cost $175 a year to replace, and I was still burning 2 cords of wood per winter.
Out of storage came the old Tempwood, and it has served me faithfully and well ever since. I heat solely with wood, and I have it down to 1 cord again, but here's why I posted in the first place:
#1, I have followed Paul's excellent advice to heat myself first, and the air around me second. I wear layers, even in the house.
#2, My house is insulated to the teeth, with R-48 in the attic, an insulated crawl space underneath, and all my windows double-pane. I don't even fire up the stove till the thermostat (I have electric heat, but try not to use it at all) goes down to 55.
#3, (and this is what I think is germane to the RMH discussion), I scrounge fuel to supplement my purchased cordwood (which I buy every year from a buddy who needs the income). Pallets are free and ubiquitous, downed wood is available, and carbide-tipped sawblades are cheap. Even better are the waxed cardboard cartons that I get from the produce department of my local supermarket. The recyclers won't take them, and if I don't, they go to the landfill. They catch fire immediately, burn with intense heat, and eliminate, entirely, the need for kindling. I have to be careful not to load the stove with them, and only use them sparingly.
Now, in no discussion I have ever seen of RMHs, has the use of waxed cardboard as a fuel source ever been mentioned. If it has, and I have missed it, I apologize. But if it performs so well in a wood stove, why the hell not in a RMH? If the idea is to heat the bricks or the cob, so that the mass will store heat, it seems to me that this would be a terrific feedstock. Certainly that has been my experience. And for RMH use, is it possible that this resource, which now is considered part of the "waste stream," might replace wood altogether? Seems to me that this would be a very "Permie-ish" activity. Thanks to all for a great thread.