I can stuff my F6 Domke bag.
What I like about the F6 is the compactness and portability, over that of the F2. All I need from the bag is to get from Point A to Point B. After that, the cameras and lenses come out for shooting. The first pic shows my F6 bag with a 6D, a 7D, a 24-105mm f4L, a 70-200mm f4L, and a 10-18mm wide lens. I'll place the lens hoods, camera strap, and movo camera sling on top of the bag. If I am traveling by car, I can place the camera slings and lens hoods in a reusable grocery bag. The second pic shows if I were to be traveling with everything in the bag.
If I were to bring the 100-400mm lens, instead of the 70-200mm lens, I'd probably take out the 10-18mm lens. I'd change to a two camera / two lens setup for the bag, with the 24-105mm and 100-400mm lenses. It is a tight fit, but it works for compactness. I will still use the F2, if I am going to bring extra camera bodies and lenses, then swap into the working F6 bag.