I use my Brain Bag as a day bag when hiking and traveling. I often carry my dSLR and other camera equipment in the bag in a separate 'camera' bag. I think an ideal solution, however, would be to have some kind of 'camera cell' or other insert that was designed to fit cameras and equipment.
Perhaps the new smaller Brain Bag would be engineered w/ this in mind.
I recently went through a crazy search for the "perfect" camera bag for my dslr, and after a while I thought "well Tom Bihn probably has the perfect bag for me" but, sadly no. It would be great if there was some sort of camera inserts that could be used in the buzz, or the brain bag, or the id, or perhaps just a camera-specific bag.
P.S. "Those" camera people are nuts (meaning they buy multiple bags, and spend a lot of time and energy analyzing and discussing the relative merits of different bags) so I think if you build it, they will come.
It would be a good bag to have.
I have looked around somewhat for a bag to protect my small digital camera but it would be a must if I choose to upgrade.
I believe that a product that resembles the MacMini case, The eM², would be ideal.