On a 40 year I don't think it matters, IMO they won't last that long anyway. The last roofer told me they will get 30 years......maybe. Of course this depends on where you live.

I think its about looks, shape, thickness and color. While many don't give a second thought to roof shingles, it is very important to the overall theme of design.

Our last was 40 year Certainteed was put on eight years ago and still looks new. One thing I don't do is walk on the roof to often or lean a ladder against the edge/lip of the shingles, it breaks down the material.

I know alot about stuff...........I'm an expert at nothing