And I suppose with the nordic climate of Estonia & Finland, fibreglass is also more suspectible to climate related effects on it? Not to mention the wintery roads that includes uneven ice and snowABS plastic, as the name implies, is hard plastic similar to the material original bumpers on car are made.
Fiberglass is more rigid and can break and crack, also more susceptible to stone stone damage.
Personally, I would never buy a a fiberglass part, but each to their own...
Reccon that is enough to seal the deal that I will avoid fibreglass.