The picture below shows my car at Carlisle with a clear 3-M acrylic bra. Honest, it's there.
Put it on in 2005 and it still looks like the day we put it on.
Now have about 12,000 trailer miles up and down I95 (Mass. to South Carolina) and back and forth to Carlisle four times from Massachusetts, as well as another 10,000+ miles running around as a car. Had one golf-ball size rock hit me just below the left headlight, puncturing a pinhole in the film but the paint underneath was completely unharmed - I was amazed, especially after the "Thwack!" of the rock hitting the nose. I'm now getting a small blemish under the film at that one spot (now about 1/8" dia.) from dirt seeping in, but will simply use some clear nail polish on that spot to seal it.
Expect to pay between $400 and $600 for the nose film. Less if the installer has a pre-cut template, and more if he/she does not. Your paint will be protected from further stone dings as far as I can tell from this experience, and it should last for ten years plus. Mine has not yellowed (it would be evident against a cream white car).
On a Black or very dark colored car it should disappear, but you will be able to see the edges if the light is just right against it. Small price to pay for saving your paint.
I would NOT try to do it yourself. find an experienced installer and let them do it. The entire nose is a compound curve and very hard to get the film on properly.
gn