Cuben Fiber Bear Bag Durability?

Yes. The 1.1 oz. CF used is more durable (at least strength wise) than most/all Silnylon sacks used. My Zpacks bag is probably 2 years old, has hit the ground a few times pretty hard, and looks brand new.

No issue with Zpacks blast … it's 1.43 cuben, way more hardcore then typical cuben stuff sack … it's pretty much bombproof in my opinion …some report theirs have withstood rodents knawing at theirs all night without getting through ….., ymmv.

My Zpacks hang bag is going on three years now, lots of rain and crappy nights beat in to it, and is my full time food bag inside of my pack, and it's in great shape. It's nice and soft now from all the use, which I would not consider a weakness. Get's washed/scrubbed out after every trip as there is always food leakage, yet the seams all look great and it still keeps the water out when hung and the food leakage in.

I appreciate the input on durability (holding up to day in, day out use) … Thanks!

RE: "some report theirs have withstood rodents"
Yes, I saw the rodent resistance testimonial on Zpacks website about their bag being chewed on all night and resulting with "some minor damage" … I'm a bit skeptical.

Depends on what minor damage means. In 2007, I was using a Spectra Ursack (S29 Green – much stronger & heavier than a cuben sack) up in the Siskiyou wilderness tied to a tree per Ursack's recommendations (according to the ranger, the particular area we were going through had bear problems reported, so we took the ursack as a precaution). I noticed in the evening there was a very determined mouse chewing on it … I thought the sack was bombproof, so I did nothing about it. Next morning there was a small hole. Too small for the mouse to get any food or too small to allow the mouse in … something I would call "minor damage" – but a potential future weakness, never the less. I think a lighter weight material would have been definitely breached.

From that point forward I do the PCT hang (if I'm not using a canister). I don't expect fabric to hold up being chewed on by animals with sharp teeth.