My real question is, I have a 50D and a 7D. I used to have a 100-400 but just traded it for a 70-200mm f/2.8 L IS USM as I really need a pro lens, and I think I'll get something different for length soon (like a 300mm f/4 IS with a 1.4x converter). Anyhow, if I mount the 70-200 2.8 or the 100-400 on one of my bodies, can I carry it at my side by the main grip? I NEVER do because I'm scared about breaking the lens mount, but I see some pros doing it now and then. I'm thinking it's okay on the 1-series cameras, but not on anything less..... what do you all think??