Seriously, I've had my GR1 since 2013 and it's still flawless. It replaced my bike messenger bags (Chrome, Mission Workshop).
It's been through sand, mud, dust and just shakes the abuse off like nothing.
I do wish half the time though that I'd bought a 40L GR2 though.
Yep. I like that the care instructions are literally to hose it off in the back yard and let it dry. This thing will outlive me.
But I main got it because I’m a relatively large guy with broad shoulders and other bags pinched my neck. I was given a Timbuk2 pack from work that I otherwise liked, but the straps were too close together. I could either wear it high on my back and have them mash my neck all day, or low on my back wear it’s much harder to carry weight.
(Side note to everyone: wear your backpack as high as possible when it’s even moderately loaded. When I see someone on BART with a huge backpack slung down by their hips, my back aches sympathetically. You want the heaviest load up between your shoulders.)
Edit: I also keep glancing at the 40L GR2, but it's just FOMO. Great bags, but huge. I don't want to schlep something that size to the office, and definitely not on some of the trails we hike.