Well it is a back pack so I would say it is intended to carry on ones back correct? For me that makes weight important. If I am canoe camping why would I even need a backpack? When ever I have been canoe camping I always use those duffel style dry bags in case of a tip over.
Because in certain places, particularly the Boundary Waters near DULUTH, are a series of lakes and rivers, and you often get out, portage to the next bit of water and put in. If you have a backpack, you can put the pack on, and portage the canoe and gear in one shot. The Duluth pack I've had (the canoe packs anyway) came with a heavy 6 mil dry bag for the inside. When packed right, they float and actually help act as a flotation device if you dump the canoe. If your pack sinks, you did it wrong.
I think the image is of being more primitive than your fellow hiker/campers. If that is your thing I understand doing the primitive thing for the fun of it. However I really don't understand it if you are mixing modern equipment with primitive. If you are going primitive buy this pack and grab a lean-to and bed roll. Make a bow and drill to create your fire. Immerse yourself in the primitive experience. I could get into that and would buy one for that reason.
A lot of guys do just that. However there are practical reasons. One is that when you canoe, the bottom of the boat gets water in it, the pack gets wet. Cotton dries faster than nylon. The outside of nylon dries quickly, but the inside stays wet a long time unless it's turned inside out to dry the inside. Water migrates in cotton from the wet to dry, so it draws the water out as it dries on the outside. So long as you don't leave it wet, it won't rot. Canvas handles long term UV better than untreated nylon. The leather becomes increasingly fitted to the wearer as the packs get worn, and if kept oiled, will not rot, either.
I still would like to here why everyone thinks this will last longer. I have been though several backpacks but I must be honest it is not because they were wore out. Truth is I bought into some latest and greatest new sales pitch from a magazine or web site and felt I could not live without a new backpack. I would like to see the backpack that is wore out and the story behind it.
Because they do last longer. We've already mentioned actual Duluth Packs that have lasted over 50 years. They used to have pics and a story ln their site about a canoe pack that was strung up between two trees to keep it from bears. The pack and/or trees got struck by lighting. The pack was badly burnt and torn, but kept intact enough to hold up the weight of one of the trees that fell and was on the way down to land on the campers.
I'm not the only one who has seen the thing nylon packs have a blowout and take a dump all over the place. Usually the culprit is abrasion or cutting on such things as sharp rocks and thorns. Canvas shrugs these off extremely well. I've walked through briars and come out bleeding, my shirt shredded, and my pack unscathed.
1000D Cordura is probably about the only material that may hold up as well. We'll know once those packs have been around 50 or 60 years.