I have looked at those packs before but its not exactly what I want. I did find this though which I think might work well.
http://www.adorama.com/LPSS100AW.html It solves the inconvenience problem at least. Anyone ever used or seen one? Natron, did you find your lowepro to be pretty high quality? No ripping of straps, broken zippers, seams coming apart, etc? Sounds like you have a pretty sweet bag full of photo equipment. And since we are photonerding out our equipment lists, heres mine (although probably wouldn't be carrying it all at once in this bag)...
Nikon D-80 dSLR, Nikkor 18-135mm, Tamron 80-300mm, Nikkor 20mm, Nikkor 55mm, generic flash, Nikon fm2 SLR, Nikonos III uw rangefinder w/ 28mm lens, and all the little accessories.
ryand, I was tempted to go with the ghettofab option on a clearance mess. bag style laptop tote by clive at EMS but it didn't seem very waterproof. My bag is bigger than I want, and the price I would pay for a good mess bag in a smaller size, I could probably buy a photo bag I don't need to ghettofabify.
Japhyrider, I found this crumpler bag which looks perfect for what I want.
http://www.adorama.com/CLCUBKBGM.html but its 190.00. Like 120.00 more than I can afford to spend.