The safety pin works, but each time you need to adjust it, you'll have to take and re-insert the pin. With the knot, it gets adjusted all in one motion. Plus, no chance of the pin coming undone in your pack and poking through other gear, or getting bent up getting shoved in the pack.
Nice pictures, it is nice to have variety. The safety pin is a simple solution.
You can use different knots too, the taunt line hitch would work as well.