Those things are constantly popping up on my ebay searches.
I'd certainly replace the rubber band as I'm sure the'd dry out and snap in no time. But other than where that picture shows could you really fit them on a lude? And the fixing they'd replace is actually the easiest/quickest screw to remove anyway, so you wouldn't be gaining much.
When you remove your bumper I assume you remove your bumper bar with it? So you have 6x M10 bolts, 2x M10 nuts, 2x those screws I've just mentioned and the 2x plastic fixings for the nostril bar to the slam panel. Can't you just get quick at removing those?
The hardest ones to get to are the M10 nuts in the engine bay behind the headlights, but I can remove a front bumper in under 5 minutes easy (including getting my tools), so for the sake of how often you're talking and reliability/safety on the road I'd be inclined to stick with the original fixings.