If I may make one aesthetic comment, a green or brown canvas pack, even if beat up, would look traditionally better to me than blue plastic in that beautiful wood interior with the wood paddles.
Okay, so I've now been obsessing about Glenn's remark about the appropriateness of a Duluth style pack for close to a week. COB that I am (that's cheap old bastard for those not in the know), I find it really hard to part with hundreds of dollars for a pack which is pretty unsophisticated. My experience with mountaineering/climbing/backpacking packs is that over the last several decades designers have made great leaps forward in both load-carrying and fabric improvements while Duluth style packs haven't changed for a hundred years! Then, on the other hand, maybe there's a good reason for this; maybe they're perfect as is....
Anyway, I'm now seriously contemplating making my own Duluth style pack. I'm a pretty good at sewing, and have Amish saddle and tack shops nearby for sourcing leather, and my brother has an industrial Juki sewing machine. Just like in my working career, I am able to 'see' the finished product in my mind, then dissect it into it's parts and fabrication steps. If I do this I'll probably use waxed canvas.
Lastly, I'll put this question out there for the regular users of these packs: What capacity/size is most useful? I've been thinking of making a large, box-style like Duluth's Paul Bunyan pack- 70+ liters capacity since I like to have everything inside the pack rather than strapped or hanging from the outside. Your thoughts?