Drake, I had originally used my Jumbo for photography use as well (both the Pantac and Maxpedition), but I've since upgraded to the Colossus and haven't looked back. It offers a lot of the great things that the Jumbo offers plus more - the biggest being a padded main compartment. Last thing I need is to be running around with all the photography gear in the bag and slamming in to things. Besides that, the padding helps keeps the main compartment in a square shape at all times - it makes swapping lenses and other gear much more easier. When I don't need my SLR body, I can even fit the full sized Nikon D3 in there with 24-70mm zoom lens mounted (with hood reversed, of course.)
I used the bag to climb the Machu Picchu Inca trail in Peru and it didn't fail me once. Carried over 25 pounds of gear on a daily basis (Colossus plus daypack stuff in a backpack, water and photography equipment) up the mountain for four days and all the gear held up well. I don't think I could have done it without the Colossus.
If you like MOLLE, both sides of the Colossus are loaded with it. Extreme versatility.