Overall great backpack. I have the original 72 with the insert but got the pro shell to use on its own. Love the waterproof feature and the durability of the material making it a great backpack to use for anything in the outdoors. My only complaint is the straps on the sides are a little small in length limiting what you can strap on the side. But there are extra loops so you can easily fashion your own straps if you need to strap something larger.
I've been using the Pro shell as my go-to ski touring bag all winter and it's awesome. Tons of room, completely waterproof, great harness system and super light. Love it.