Carbon fiber, like most materials, comes with pros and cons. Here's a few that relate to pack design:
Pros - High strength to weight ratio and can be custom designed for shape and flex.
Cons - Shape cannot be altered by user and when it breaks it's broken.
What I find interesting is the sudden resurgence of CF in pack frames. Kuiu, Kifaru and Titanium Goat all have new packs out this year with CF in one form or another. My first real mountaineering pack, a Gregory Denali Pro from some 20 years ago, actually had CF stays. It was touted at the time as state of the art and the next evolution in pack frame construction. You can imagine my surprise when a few years later Gregory went back to aluminum stays in the same pack. :-)
