I don't seem to have any degrading of my roof material after 9 years and mine sits out in the new England weather. I think mine is called DICOR BRITE TEK TPO material, heavy vinal texured surface 1/16 thickness with a felt backing ,seems to be a pretty tuff material to me.I have backed into tree branches and broke them off without any tears in this material, does not seem to create black streaks either. I have one of the early B-Plus units so it may have been a material that they were trying out but became a cost issue to them so they decided to go with rubber. I think the coaches with the old style front cap may all have this material. I don't recommend anything that stays in contact with the roof where wind could cause chafing of the two surfaces or hold in moisture.
Dario