I don't know anything about SEA, but I've been travelling around Mexico and El Salvador with this pacsafe camera bag:
It has some extra clips for the zippers and it is easy to sling it around to the front (when you're getting on a busy metro, for instance) It is also easy to bury things down inside it to make things a little more difficult for would-be pick-pockets.
I haven't had any close calls (to my knowledge) so maybe it is just piece of mind, but I've been very happy with it.
It isn't very big, though, so it depends on what equipment you have. I'm carrying a mirrorless Sony A7 Mark II with three lenses total (though it is a mirrorless camera so they're all pretty small), a Canon flash, hard drive, and a Surface Pro 3, with all of the chargers, extra battery, SD cards, etc... and everything fits quite comfortably.
I also have a shoulder sling to hold my camera which I love for shooting, but also means it'd take a little extra effort for someone to snatch it out of my hands and run with it.
That said, the Sony isn't a very big body. If you've got a full-frame SLR or something - or you're travelling with a laptop much bigger than a Surface or a macbook air, that pacsafe bag may not work for you.