One thing I found with an Earth is you got a massive amount of water to heat which takes more fuel and the 2 things cooling this water is heating your house and the weather outside. With this Rancher I have I looked at the insulation and I have 2 inches between the firebox and the cold weather and it's not even a full sheet, it's about 13 inch wide panels stuffed between the framework on the stove so that's where some of the heat goes, As far as the half inch thick firebox, I never really hit the side, I hit the chimney that sticks halfway down into the firebox, kind of limits the size of logs I through in there but yeah you can put alot of wood in there as long as there's no fire rolling out the front, in my case I have no problem with since with the '09 model I have the fire goes out every time I shut the door and so when I feel the need to put wood in there there's no fire to hit me in the face, I rebuild my fire quite a bit. This has something to do with the air flow being the vent blower is built in behind the stove,blowing air into the ashpit,not into the firebox, but I'm sure they've corrected that problem.
As far as effencieny goes, I talked to a guy that has one of these and he says he goes through 6 cords a year so thats one thing you need to do no matter which stove you buy , see how much wood you'll go through and they'll all give you the burn time, temperature settings speach, how warm you keep your housewhat type of wood but we have a gas heater, gas stove, gas water heater and gas dryer and we used about a tank a year, around 800 bucks so if you cut your own wood thats great but if you run outta places to cut and have to travel , then buy, that could run into some bucks. I've got my own wood but when I rebuild a fire as often as I do I waste alot of wood , after all 230 gallons of water on the othet side of a half inch steel wall takes awhile to heat on a cold night with very little insulation.
As far as dealers go, the only one around here that I know of doesn't carry replacement parts , when the pump went out the company shipped it supposedly next day but it took a week to get here ground delivery and when the electronic temperature control quit working that took a week , but that was delivered a couple hours north of me instead, I couldn't go pick it up so it had to be reshipped.
So all these things should be considered, parts fail, can you get a replacement on a cold winter night , even though the firebox will last a lifetime, will you be able to use it. Effeniency covers alot of ground, I just got done rebuilding my fire again,it's 3 am and I should be asleep. Don't talk to salesmen, talk to owners