The backpacking/ultralight side of things is, in many cases, decades ahead of the hunting/bushcrafting/military side in terms of materials and design. Yes, wool is great, and may be irreplaceable as a long term durable fabric. But holy cow, if I'm out doing strenuous exercise in the cold for days at a time, I sure like polypro and fleece.
And then there are backpacks. 6-8 pound mil-spec tactical packs in the woods? Ugh.
You're saying I should dump my proven comfortable and durable wool, cotton, canvas, and wood in favor of noisy, flimsy, uncomfortable, and expensive plastics? Doesn't sound like too good of an idea to me.
The latest trends aren't always the best. Just look at the 80's.
With natural vs synthetics, I flip flop like a puppy on crack. But as far as trendy, check out all the Merino Wool stuff that has come out recently. Now yer talking. Combining space age design, stitching, and fit with the best of natural fibers.
No, really not telling you what you should do, or wear, or prefer. Really. There are a lot of ways to skin a moose.
I've got plenty of wool and leather that I wear outside. Sometimes I wear full grain leather boots, sometimes all synthetic.
Wool is, as I said earlier, durable, comfortable, and tough. I wear it all the time. It's also pretty bullky and heavy if you're moving around a lot (or far). Hillary and Tensing wore it to the top of Everest, which is pretty cool. I'd bet my favorite knife, though, that they'd have traded it in a heartbeat for a modern synthetic/down climbing suit. Imagine what they would have done to get out of those leather boots and into some insulated modern mountaineering boots.
I would agree with Joe that some of the new merino stuff is close to being the best of both worlds. Spensive, but nice. Some of my poly longjohns are 20+ years old -- they've long outlasted the scratchy wool they replaced. Both are great.
Canvas? I like Carharrts for work outdoors close to home, but would never wear them in the woods. Doubly so for a canvas pack, which to me is a eight pounds of ill-fitting misery. My 60-liter Gregory pack weighs less than three pounds, and is more comfortable than any backpack I've ever used.
Cotton? Apart from boxers, that's for home.
Sleeping? For me, there are few things as liberating as carrying an 18 oz. 30-degree down sleeping bag that compresses to the size of a football. An ancient and tested insulation form, coupled with modern materials, and super lightweight. Win.
Your calculation might be different, which is great.
This is all to say that there's no single right solution -- there are lots of good materials, and the smart money is on not being too wedded to being a purist, whether in the name of traditionalism, or technology.
One thing I'll say unequivocally, though. You'll be hard-pressed to convince me that a canvas pack is anything more than a retro fashion statement. You can be pissed at me for that.
