I've had a Blaze King "King" model in the basement heating my 2,000 sq. ft. home with 1.5 levels above it. We just went through a cold spell of steady -4 F / -20C for highs to -35 F / -37 C for highs and lows for nearly 3 weeks and despite all my large windows, the stove heated the place very well. My house is quite air tight otherwise, though still not 100% finished, still needing siding on 2 sides.
I only ever use the "Normal" #2-3 temperature setting on these coldest days, or otherwise it would just pump out too much heat. Normally I have it set on 1 +/- so long as the catalytic converter is in mid to mid high range, as I want the stove to burn as clean as possible. If I burned it on Normal during the normal winter days, the house would be too hot and I'd not get the longer burn times. Normally I put in 2-3 halfs or 8+" rounds of lodgepole pine at 8 am and then again before bed at 9:30 pm and it's rarely ever completely burned up and the converter is always active. I rarely ever completely fill my stove vs. just partially filling it twice every 24 hrs.
40 hr. burn times with a completely stuffed firebox could be possible in perfect conditions on a low heat output but heating for what size of space? I regularily fill mine up and go away for 2-3 days and still have coals and a warm house for the cat when I get back, but of course not on these coldest days. On the coldest days, I burned about 25% more birch than a 15 F / -10C average day, and for those warmer temps I usually just burn pine and I save the birch for the coldest days.
It will certainly pump out the heat with long burn times, especially if completely loaded. I easily get 12-14 hr burn times on the not too cold days and only partially filled. It is also supposed to burn very clean with the catalytic converter active, and that is as important to me as the heat and the volume. I only ever see blue smoke coming out on initial starting and never once the converter gets to be active. The converters aren't that much in cost once every few years (I'm on winter #3) and for me it's a worthwhile investment for less air pollution. I wish everyone in the valley used them as otherwise the valley gets choked with a layer of thick blue smoke from all those old, non EPA stoves, and the growing number of outdoor burners.
Compared to my previous and older RSF that came with this place and I used only one long cool winter, I burn so much less wood and get much more heat and cleaner burning, and minimal creosote, with a thermostat that works really well, that there is no comparison. So I'm a happy user, burning 24/7 through about 1.5-2 cords from early October through April.
It was expensive, but worth it, especially compared to every other stove that I see at other peoples places. It certainly won't be a bust for you. I don't know how it compares to other newer models out there. It is well made and very heavy gauge. I also cook on it and not just reheating meals, so that cuts down my propane stove use in winter to nearly nothing.
