None that I've run into. I use the Heetsheets bivy version, which I also use as a BP liner in bad weather and to keep the rain off my feet and legs when it's precipitating. The material is resistant to tearing, lightweight (3.5 oz for the bivy, less, I'd guess, for the blanket).
One proviso: If it comes with a stuff sack, dump the stuff sack. Just fold the thing up and put it in your pack or use it as a pack liner. I never successfully got it completely back in the stuff sack, anyway.