I understand the advantage of a fiberglass roof over rubber, mainly stronger resistance to damage from branches and a longer overall life. However the main failure of most roofs is leakage, which usually happens at a junction. In that case, they are the same, aren't they? A fiberglass roof has the same number of seams and penetrations as a rubber roof right?
From a maintenance standpoint, they are both going to require the same inspection and resealing on an annual basis. The rubber will need a re-coating in 10-15 years though.