I could be wrong, but it seems to me that cat stoves have the best technology for getting good secondary combustion and clean burns while at the same time minimizing potential overfire and heat loss due to excessive air flow through the stove -- this due to the ability to burn smoke at lower temperatures. So they are less likely to invite tinkering, no?
Downdraft/crossdraft stoves like mine seem to have the worst technology, requiring the highest firebox temps and greatest potential for heat loss up the flue in pursuit of a clean burn via rear burn chamber. (Seems like a lot of overfired downdrafts have popped up on this forum, too.) I have done some temporary mods with secondary air, but really ought to have a pipe damper.
The vast majority of EPA stoves, with tube technology, fall between the other two types. But basically, we all have a variation on a metal/stone box that lets us each heat our homes pretty clean for pretty cheap, with something pretty to look at, too. No complaints here... (today).
