While I was hunting around for man-bags, I ended up revisiting the Pacsafe website and looking at all the anti-theft features of their bags. Admittedly, I don't think their products are as good looking or functional as my TB bags, but sometimes I worry about using, say, my large Cafe bag, in crowded situations (e.g., packed subway) given that there's no way to completely close off the top from wandering hands. I doubt anybody is going to slash through the shoulder strap anytime soon, but the bottom could be cut through given a thief with a sharp knife and the right opportunity.
Has anybody thought about how to prevent casual theft, or a way to make TB bags more secure? Pacsafe has a metal mesh bag that can be used in other bags, and I'm wondering if something like that can be used in TB bags.