5100i insert here and happy with it. Agreed, seasoned wood is the key, I'd say minimum 25% more heat with 2 year seasoned oak vs. 1 year seasoned oak. Also, air coming in has to be choked back about 25% from wide open with 2 year seasoned wood or the chimney temp gets too hot. No gauge, but glowing red is too hot in my book.
Some observations, but I suspect its the same with other stoves.
Can't throw wood in, that will crack the fire bricks. It has to be placed in the firebox, then shoved in place with a poker or tongs.
It burns better when putting wood in sideways vs. long ways. (air comes into the stove from the top front)
Coals piling up are an issue, no grate, wood is laid on floor (firebrick).
A free standing wood stove (I think) puts off more heat than an insert. BUT, in my house there is no room for a free standing stove.
If air is choked down, it will burn more than 12 hr. If air is wide open, a load will last 4-8 hrs depending on what type of hardwood.