Scott Allredwrote a review of Osprey Packs Raptor 18 Hydration Pack - 1100cu in on June 26, 2012
This is exactly what I was looking for. I can fit a compressed down jacket, rain shell, and some snacks in it and still have some room. On a hot Utah day the bladder will last me between 8-10 miles depending on how hard I am working. Over all the pack is extremely well built and comfortable.
The bladder design is genius. It has a firm packing, which not only protects it, but also acts as an internal frame for the pack.