I have a couple of Paul Bunyan Duluth packs.  Packs don't get any bigger.  As pointed out previously, the canvas packs are surprising water proof.  Leave the packs out all day in a rain and the inside will not be wet.  My packs are not waxed.  This doesn't mean you can leave the packs in standing water, but if they are hung up, the inside will stay dry.
The life time guarantee on Duluth Pack is not all inclusive.  The life time guarantee refers to the hardware and the straps.  The guarantee does not include wear and tear.