Hydrapak's hard shell Borracho is a bit of a conundrum, as it's heavy, boxy and not really very much fun to ride far in.
The elastic and metal helmet retention web was also rather punishing on tired, fumbling fingers. There are plenty of pockets to play with, and the unusual construction means that there's some rigidity to help keep awkward loads (like full-face helmets) in place. The chunky, solid harness helps with this too, but it's still a pack for riding to the trails, rather than just riding in.