Fiberglass will cack just as easily as CF, just CF will actually snap off in pieces. I'd go with urethane or ABS. My lip is ABS and I have to say at this point had it not beeen ABS it would have been destroyed about 10x by now.

I'm not trying to push ABS just cause I own one, but rather am trying to look out for a brother, as I'd hate to see you spend money on a part only to have it destroyed a week later. My friend installed the exact same lip I have only in CF, and I shit you not 2 days later he destroyed it and a big chunk was taken out of it.