I don’t think I’d like the knife one. I’d stick it in my pocket of course like any other knife or memory stick, and that one looks like it would accumulate crap in and around the USB connector (even worse than a generic stick with no connector cover).
It is a key chain thing, since it is swiss army who typical do an alright job concerning quality (like their watches), I am sure the recess for the usb is tight as any other high quality connector.
I don’t usually carry a knife, pen or key light so if I have to carry a usb, might as well carry something that does more than one job. This was what made me even think twice about it other than the cool factor.