I am also working on redoing my Roof, the FatMat started to fall (as expected) from the heat. Although the FatMat xxx works nice and not a bad price, it was not made for high heat and it will most def. fall off the roof if you live in a hot summer area. HEADS UP!
I am now with SecondSkin and I am in the process of covering the roof with Alpha Damp. I am about 7 sheets in, along with some more Foam in the hollow areas, and I am loving the product! I'll post some pics / vids soon. But until then, here is my latest vid..