Big brother to the F5XZ?
Just came back from a month travelling in Europe and I had to let you know that the F5XZ (rugged wear) was awesome. Considering the weather (very wet), the bag worked flawlessly. The biggest advantage with this bag was how unobtrusive is is: it doesn't scream "expensive camera inside" and barely got a second glance.
What would be really nice would be to get a bigger brother to this bag for those times when you need just a bit more, such as an additional larger lens. This would also allow for a larger opening on the top and my one complaint with the existing bag is that to opening is a bit too narrow for a prosumer SLR. This would also allow for a slender pocket on the back of the bag to carry a netbook/small notebook as well.
One other thing that would be nice would be to use less velcro on the flap (maybe just is the corners) or use snaps instead. There is nothing worse than standing in a large cathedral, quiet and solumn, people silently praying and hearing the lengthy "RIPPPPP" of the overly large strip velcro resonate off the 100 foot high ceiling and every matching stone wall. It is about as subtle as letting off a small cannon. More than once my face turned an interesting shade of red while extracting my camera from the bag...
Other than that, the F5XZ is perfect and I'd love to see a larger version one day.