Yeah. I brought up Ventile in the specific context of what's the best overall, and agree that it's real expensive. I can't afford it right now either, but I am considering making a special effort to get some later.
David and Jeff are two of the more experienced people you'll find, and they got the Fairfield stuff. Maybe there's better stuff out there, but that's what they got, and I've touched it, and they believe it's good for the task at hand.
The climate such that it is here, I suspect mildew can be avoided by drying thoroughly before storage. That said, the chemicals probably saved me a lot of grief when I had to leave camp after sticking an axe in my foot. It was below freezing when I left and the tent was packed with ice on it from when we moved it last, and nobody was around to dry it out for a few weeks of damp spring weather. That was a case of accident (user error), and having my mistake softened by chemicals.
I know canvas can catch fire, and that can be super dangerous. I believe that Snow Walker's Companion says or implies they don't use fire-treated fabric, and the consensus vibe I get here is that Alaska Tent & Tarp has adopted their "no stove jacks without fire-treated fabric" out of liability concern, and doesn't necessarily reflect the optimal point on the risk-reward scale of utility. The cheap dome tent I happen to be in right now has a huge fire warning tag because of liability issues too. I'm not saying it's not a real concern, but it does seem to me that people with more experience than I have are against using fire-treated canvas.
BTW, I think I have 10-20 yds. Of 10 oz. of the robust duck mildew/fire treated stuff up here that I may not have a use for. That doesn't help you in America today, but it reminds me that someone has mentioned maybe using fire-retardant canvas on panels closest to the stove jack in a targeted manner.