i have the fibergalss ones, all 4 of them. I don't have any complaints other than the bumpers rubed on them in a small sopt and went through the paint and now hey have white spots, but abs would do the same thing.
i'd go plastic if i were you, just because its flexable and won't crack as easly, but i haven't had any problems, and i dont' think many people do. price is probably the biggest difference.