On the subject of using diamond knots on a backpack for light pickpocket deterrence, and a follow-up suggestion to use S-clip carabiners, reader KokoTheTalkingApe, had a great point:
I thought the point of the original complicated knot business was to put up some initial resistance to would-be thieves, and to LOOK as if the knots would be difficult to undo. Which they do, even though they’re quite easy to release. Also, the price is virtually nothing.
But it’s obvious how s-biners work, so I’d imagine they wouldn’t deter thieves as well as the knots. If the s-biners lock and if the lock switch is underneath, then they might actually not be so easy to open, but the idea was to keep them from even trying, wasn’t it?
If I wanted to make it actually difficult to open, then I might try some other strategy.