Ok, I replaced the office stove with a Jotul F100 last year. Moving it up to a F3 CB this year and moving the F100 to the warehouse for heat. Next in line is the replacement of the big insert in the house. I figure this year to be its last season so the replacement shopping has begun. What I don't know is what stove I am going to need to give me comparable heat. Given that the old environment abuser has a four cubic foot firebox and gives me long burns and pretty much the perfect heat output needed for our house. I very possibly am going to end up in CAT land but I don't know. Anybody have any experiences to toss in regarding their move from the old tech to the new tech and any guesses at how much smaller I can go with a new stove and still have roughly equivilent heating and burn times? I know it is all subjective and depends on the operator and the wood as much as the stove, but personal experiences about perceived output old to new are probably more meaningful than lab stats. And the big CATs mostly appear to need eight inch flues which ain't gonna be happening in this chimney. After the hell of getting that double wall six inch liner and a bunch of rockwool in there, it stays in there. All is appreciated.