so in years past i have used one camera and had one as a back up camera and swapped lenses as needed.  my 7d is a work horse and i love it.  so i am not replacing it i am adding to it.  the 24-105mm L will sit on the 5d ii and the 70-200mm 2.8 is will sit on the 7d to get that extra zoom reach.  i love the 24-105mm on my 7d its the perfect all use camera lens combo and is what i use 95% of the time for most shoots.  but for wedding this season i am getting a fancy belt that holds 2 cameras. one on each hip ill still have a back up camera. so i have 3 pro bodies.   i can have any lens or camera break down and i wont skip a beat still being able to use 2 cameras. but we will see i can always swap back to one camera if i feel the need or want.  ill keep you posted i might just shoot with the 5d ii and use the 7d as a back up but i love the option of using full frame and a 1.6 crop cameras making all my lenses have double uses.