Glad it's worked out for you, but lets be fair.
Apples to oranges. Your house layout is not standard (except in some northern European countries). For others to equal that set up, blows your economy comparison so far out of the water, . . . it'll be bone dry by the time it lands.
And, I'm not sure where your getting your 17, and 27 feet internal flue length claims from, but that's physically impossible for any base burner I've ever seen. BTW, cherry picking examples and using exaggerations to bolster a point only makes that point look that much more flawed.
Plus, have you added the cost of electricity needed, to your yearly heating costs ? I could up my heat gain by simply putting a small fan on the floor behind the stove. I know people who do exactly that with these old stoves.
And sure, I could put my hand on double walled pipe near the stove too. That's why codes require it in many installations. However, it doesn't make a stove more efficient. What are your actual flue gas temps inside that double walled pipe compared to the flue gas temps at the same distance from a baseburner? And for sake of argument, I'll throw my kitchen range into the baseburner category because it uses the same technology, from the same time period, made by the same people as the base burners. I can put my hand on the single wall pipe
3 feet above the stove top. The stove took so much heat out (without the need of additional electric devices), to the point that a double walled pipe isn't needed.
Long indoor pipe runs are nothing new. Look at old photos from the mid to late 19th century. Many times the stove pipe ran on a very shallow up-slope the length of a rooms, or churches, or public buildings.
And, what kind of temps do you get when the power's out ? Alot of north country places have these non-electric stoves because losing power during the coldest months is not a case of "if", but "when". I specifically looked for and got non-electric stoves because I didn't care for the times that I've been here without power. One was three days with no water because the pipes froze and it was 20 degrees in my kitchen and the only bit of heat I had was heating up pots of water on my gas kitchen stove.
If you look at houses built before 1900, most chimneys were centrally located. Many were two, three and four sided fireplaces that fed into a large central brick chimney that used all that brick as "thermal mass". My house was built in 1866. The main chimney which originally had a coal furnace hooked to it is in the center of the house. The large fireplace was the original kitchen cook fire place. Even though it was changed into a "sitting room" (living room) in 1892, it still has the swing-out wrought iron cooking pot crane. At four feet wide and thee feet high I can't feed wood into it fast enough ! The kitchen range was and now again, is plumbed into the original kitchen stove outside brick chimney on the rear of the house. Unlined, very tall, it has terrific draft !!!!!
Since I started using a mano gauge a couple of weeks ago, I've been charting the times and temps to find the "sweet spot" for damper settings. I'm using a hand-held IR gun which is much more accurate for reading actual surface temps, not just doing guesstimates of what it's doing.
Damped down last night at 8 pm, with the ash door primary =.045 inch openings, no secondary air (other than leaks), and the MPD fully closed. When I came down this morning at 7:10 am, the two top plates over the fire box read, 647 F and 642 F degrees. The single-walled stack, 36 inches above the stove, read 106 F, The right hand end of the water tank, one of the last places the flue gases get to, was 126 F. My new Dwyer model 25 manometer was reading .01. The pictures below are of this morning's coal bed after 11 hours and 10 minutes showing it's still up to the top of the firebox with at least another hour or more of coal before needed to be refueled with more coal.
BTW, so far, except for the electric fan, you haven't mention anything new that these old stoves didn't have.
And no, you don't have to spend $8000.00 for a high efficiency old coal stove. You can get baseburners, or parlor stoves with preheated primary air inlets and back pipes for less than that. You can get 2-3 restored Glenwood Modern Oaks with back pipes that are fairly close to being as efficient as the best baseburners for that $8000.00. And, I can buy restored kitchen ranges for less than half that.
Now, tell me again about the 6 pots worth of large meal you cooked and baked all at the same time on your stove, during a power outage, . . . while still efficiently heating your house, . . . plus, making over 4 gallons of hot water to wash the dishes with afterwards. All with the same amount of coal ?