I also highly recommend F-Stop. I was looking for exactly the same thing as you. I've been through several backpacks trying to find a good hiking photo pack, most recently a Dakine Quest. But I just got an F-Stop Loka and it is perfect.
I have a medium ICU, which perfectly holds my 7D, 17-55, 70-200, and 10-22, with the hoods. My Gitzo 1542 tripod also fits perfectly on the outside. I put it in on the side using the pocket and straps, but it could also go on the front using the straps.
Inside I was also able to fit my 1L camelback water bladder, paclite waterproof pants and jacket shell, gloves, GPS, flashlight, leatherman, and a little bit of food (two PB&J sandwiches in a plastic case and a few cliff bars). The bag was the perfect size for all of this and was pretty full. If you needed to hold more gear or food, definitely go for the Tilopa or Sartori.
The bags are really, really well made and comfortable. And the flexibility of the system is awesome. Plus they're really good looking packs, unlike mst photo packs.