I only use down bags. Like Randaddy, I use a water resistant compression stuff sack and pack them in my Watershed dry bag. The only issue I have ever had with them is dampness from dew when I sleep without a tent on certain trips. If you protect them, you should be good. If you like to sleep without a tent, then you may have issues.
"We are all visitors to this time, this place. We are just passing through. Our purpose here is to observe, to learn, to grow, to love....and then we return home."
Australian Aboriginal Proverb