Front bumpers are prone to stone chips as most people know.
If you have a Carbon Fibre front bumper and it gets stone chipped how do you fix it? I don't think its possible tbh.
if it's just stone chips, all that happens is the clearcoat is scratched. you can sand it down and have it clear coated again. i hit my carbon front spoiler on a sidewalk HARD and all that happened was it was a bit scratched. sanded it down, clear coated it and its like as new (of course it's 6 layers of carbon...bulletproof)
the thing about a front bumper is, its the most damage prone part of the bodywork. you really wanna spend so much money on a part that's the first to take damage? and it's got no significant weight gain...