I personally think any camera "backpacking backpack" is a huge waste of money and the people buying them are not really backpackers, they just like to think they are. Weight is a huge burden when backpacking, and all of those camera packs are ridiculously heavy. For example, the 35L Rover Pro is 5 pounds! I think my main pack is 1.5 pounds for comparison...
Just get a pack that fits you well and use the money you save on a good down sleeping bag. If you go this route, get lens cases for each lens and make sure it has a belt loop. When you get to where you are gonna be shooting, put each lens case on the waist belt of the pack and unstrap the tripod from the back.
Works perfectly for me all the time. I had no complaints when I was doing 18 miles and 10k of elevation gain a day through the snow. Plus my pack has loops for ice axes. I could be wrong, but I have not seen that on any camera pack.
Niterider is being brutally honest. If you want a photography backpack to carry lots of camera gear more comfortably on a day hike, by all means, go for it. If you plan to do real hiking and live out of your backpack for 2+ days, do yourself a favor and get real hiking gear just like you already do for real photography. Learn how to camp, hike and carry weight. Get in shape. Camp with others that are more experienced and become a knowledgeable outdoor person. You'll likely spend over $1000 - $1500 before you're done and you'll still lust after some better hiking gear. And you will likely devise a special unique method and system for your photography so you can enjoy hiking and photography simultaneously.