I have the old version 3n1-33. Works a treat and i've traveled to China, South Africa, Prague, Italy, Paris, Monaco, Nice, Bangkok, switzerland. and a few other countries/cities with it.
Never had anything stolen.
However as a sling, not exactly a great idea if you're carrying loads of gear. I had 2 camera bodies at some of the countries along with 70-200 f2.8 IS II, 50 1.2L, 16-35 f2.8, 2x flashes, macbook pro 15", batteries etc.
I'd challenge you to carry that kinda that kinda weight on 1 shoulder. LoL
It is an awesome bag, I have the trolly as well, but have found the trolly to be a bit of a pain sometimes when turning too fast and the bag not turning with the trolly and misalinging itself.
I like the new version with extra pockets and all. Am considering getting the updated version in the future.