The best insert!?!
When I started designing the bag I based it on a fishing bag and had a row of three compartments then the back was empty. For fish.
Former NY Times photog and later Director of Photography at the Seattle Times, Gary Settle suggested a six-pack. And this evolved to the four compartment insert, but I always offered other inserts. Depends on how often you store the camera with long lens.
The new four compartment with adjustable "X" divider works best for me today with the wider-fast zoom lenses. I basically have made it three compartments so I have enough room for the lens shade.
The F811 - Photo Laptop is my favorite because I like things to stand up, This bag as the depth to allow me to keep a camera attached to the longer telephoto. With things standing up the bag wont stick out and is easier to get through doorways and crowds. I always hesitated in building the F! bag, thinking it was too big to get through crowds and under plane seats. Finally got talked into making it when some photogs insisted they would carry it all! And they needed lots of lenses to shoot both in color and b/w film.
Today, one camera body does it all with digital, so why have an F-1 sticking out banging into things, try the F811.
I also take the padding out of the front side of the insert, so there is only padding on the ends and the back side. I always feel the stuff in the outside pockets serve the same purpose as padding. The pads need to be flexible to hug your body. A box on your side rolls around and keeps sliding off your shoulder. (I've actually removed the padding sewn in the outside walls on the F811.)