if it gets broken you can take it to a bodyshop and have them fix it and repaint it where as if you have a polyurethane or abs plastic lip if it breaks it is alot harder to repair and make look good

I will never go with Fiberglass is easy to brake. i had Mugen Replica bumper, front lip, side skirts and rear lips. side skirts and rear lips are ok but for bumper and front lip, i wouldnt go with fiberglass. also bodyshop hated to work on them.