I've been carrying my quilt in a DCF roll-top (dry bag) stuff sack in the bottom of the pack out of paranoia, and it does become a rock in the back at times. This probably is overkill, since I also carry a trash compactor bag (folded up) with the thermarest 'tap' in the corner which I use to inflate my Xlite pad -- so I'm grateful for the reminder to use the compactor bag for the quilt with the top folded over. My main pack is the HMG Windrider, so it would take a real gullywasher rain to cause any problems.