I'm a big fan of Kata bags but honestly I've yet to find an idea solution that really meets the needs of a hiking bag and camera bag at the same time. For shorter stuff (less than 10 miles) I generally use my photo vest with a couple of lenses in the front pocket and water in the back pockets. The camera goes on my tripod over my shoulder.
For backpacking trips I scale back and use a regular internal frame pack. The tripod goes on the side and my 17-40 fits neatly inside my mess cup. I use a Lowepro toploader bag strapped to my pack's chest straps for the body and my 24-70. I find that if I have to stop and open my pack to get the camera out I use it much less often. This setup works for me pretty well.