I ran into a site that makes me wonder a LOT if this is a good roofing material for any site that isn't cream puff soft: http://www.ondurasucks.com /
As you can tell by the name, it's a burned owner. He's mad as hell over Ondura refusing to honor a warranty on his roof in Hawaii that went only two years before the coating began to rot and peel into his drinking water. The company blames his having TREES near his house!
Anyway, maybe this product isn't really good for most areas. Check out the site. The guy's story isn't hard to understand.