Generally I use the sling when I'm out walking somewhere in public. If I'm at home or somewhere I can set my camera down without worrying about it, I don't use any straps or slings.
I use a
'cheap' sling from Amazon that clips to a plate you screw into the tripod mount. Even though it doesn't cost as much as a Black Rapid it's pretty sturdy and works great.
(Link) As far as I can see, the weakest point would be if the metal swivel on the carabiner wears, but that would be after very long term use and
I see someone found a quick fix (though it takes away the swivel aspect). I've used mine for about two years and it's still good, so I'll just replace it for <$10 if I notice it getting loose. One advantage over the Black Rapid (aside from price) is that the screw that holds the mount plate to the camera's tripod mount has a female thread on the other side, so you can mount a tripod plate to the sling to use both at the same time. I've only done that once, but it's nice to have the option.