I use a Velocity 7 for a 5D(w/rrs L bracket), 24-105 is, small flash and a Kenko 2x converter and love it. I use a Velocity 8 when I add the 70-300. The 7 is too small for the 70-200 2.8 but the 8 might work. I hike with the 7 all the time it is now what I use 90% of the time. The 7 fits nicely into my carry on bag as I fly a lot. I would buy both and switch bags as you need unless you never have to pack small and light then the 8 would hold most of what you need. in the front pouch I have a cp filter, white balance filter, battery, CF card and more
Marc