Silnylon is flammable. Pretty much everyone I know with a stove and silnylon shelter has a few small holes (generally pin size) from cinders coming out from the stove pipe. If they're big enough to leak, they are easily repaired with a drop of silicon. I don't know anyone who has set theirs on fire. As phat said, a good stove jack is key. Burning good wood helps. No pinecones! <img src="/forums/images/graemlins/wink.gif" alt="" /> You can get stove jack material from Kifaru or Ti-goat -- it's a heavy, inflammable cloth.

I couldn't get through that link to read about stove durability but did speak with some very experienced stove builders and users while building mine, one of whom used to make commercial stoves of this sort. Although it certainly won't last as long as a good stainless steel one, the consensus was that ductwork is quite suitable for stove building -- just be sure to burn off the galvanized finish before using it in a tent as that stuff is toxic. I had to use a propane torch for spots that didn't heat up enough from burning the stove itself. The main cylinder is the part most likely to wear out. It cost me $9 for a piece big enough to build at least three stoves. I'd imagine that the rest of the pieces will be reusable for quite some time as the ends don't seem to get nearly as hot as the body.