I can fit my 70-200 2.8L IS attached to my 1Dmark III with RRS L-Plate in the middle slot. Sure it's tight to close the bag but it fits.
Also many other things fit as well.
I have the two side slots split in half for extra space.
On the right slot I keep my 85L on the bottom and 16-35L on top and a divider to keep my 580ex in the same side slot.
on the left side slot I keep my 24-70L plus pocket wizzards or extra flashes.
In the middle slot where the 70-200 goes there is still extra room so I keep batteries, memory cards, biz cards, flash module cable, etc... And on the front pouch I keep my RRS wedding pro flash bracket (WPF-1), it's soo compact it fits right in front with the off shoe cord.
If you're a girl or small guy my bag might seem heavy, but for me it's perfect.
I live in the city so people carrying messenger bags are everywhere so I have less chance of being targeted carrying a big camera backpack.
This bag is very stealthy, low key, and keeps your lenses easily accessible. Weight might be an issue for most, I still seem to find my self putting the bag down when I get really into shooting what's going on in front of the lens. But I generally ALWAYS have the bag at my side.