Certainteed DiamondDeck

Anyone have any opinions on Certainteed’s DiamondDeck? Roofer is providing an excellent price to upgrade underlayment to Deck Armor or DiamondDeck. I am getting certainteed shingles, so I will probably stick to their underlayment so there is no finger-pointing if there are any warranty issues.

Thanks.

I’ve used it several times and have had no problems with it. It does not “breathe” like GAF’s Deck Armor but I think that benefit may be overstated if the attic is properly ventilated.