Backpackers: how do you carry your fixed blade and psk?

[Joben]

I don't want to look stupid, but how secure is that dangling sheath/ tip up carry, especially with all of the jarring of a hike? Has anyone had a knife slip out of it's sheath?

I have, my tiny little KA-BAR TDI LDK fell out several times until I added a tension adjuster screw to the sheath. After that not a single problem.

Which in a way makes my actual point, which is that if things are designed and built right inverted carry works no problem.
My Izula which is much heavier than the LDK, and would seem more vulnerable is not. I littleraly can't shake it out of it's sheath if I try.

But it is something you should pay attention to when the knife is new, and maybe after a month or so when it's worn in a bit.