>>29052695d MkIII with the 24-70 lens stays on my shoulder at all times when travelling with the 50mm and the camcorder in my jacket pocket - it never leaves my sight with the exception of airport scanners.
Fortunately I've never encountered any sneaky motorcyclists.
However I do have a little unconventional tip for making sure your lens isn't stolen - by breaking off the lens release button it makes it near impossible for a pickpocket (or even airport security) to easily remove your lens. I'm able to activate the mechanism with my fingernail so it doesn't hinder me at all.
