I have PPF on the front end of my car, combination of Suntek and 3M Ventureshield, latter for the areas that get more debris. Yellowing is not a common feature anymore, the films have a 5 year guarantee in any event and I have mine ceramic coated too which enhances the UV stability of the film. It can also be machine polished.
It will stop most stone chips, even car park bumps to an extent but sharp stones and bricks will cut it and chip the paint.
Only downside, if any part of a car has been repainted to sub optimal standard then if you remove the film it will take the paint off too. Just had that with my car, poor front end respray by Audi prior to them selling me the car.
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