I have one in my day pack, but I consider it more of a very thin and small tarp than a blanket. As a way to block wind and rain it has some utility. But it really has no utiliy as a blanket that I can see.

For as thin as they are, the couple I have opened up were pretty tough, but pretty noisy too.

Ah, Glasshoppa, you have struck upon the very essence of my initial post: to encourage everyone to see just how much of a "blanket" their "survival blanket" really is.

Personally, I have to say I became "warm" very quickly as soon as I attempted to wrap up in my cheap sample even tho it didn't cover worth shinola, and tore easily. I was very impressed at how much even this crappy example seemed to reflect back my own body heat.