I went with the synthetic sleeping bags instead of the down and I'm glad I did after reading this account,

http://www.nwhikers.net/forums/viewtopic.php?t=7963667
"We left on a short overnight hike with a forecast of 3 to 5 inches of snow followed by rain and wind. Perfect to test new gear. What we got was 3 to 5 FEET of powder followed by torrential rain. We just couldn't make it out without snowshoes. Took 7 hours to go 1 mile.

So it ended up with 4 of us in a 2 man Sierra Designs tent for 2 nights. We immediatly went on reduced rations and pulled together. We had one synthetic sleeping bag. The other 3 were down and worse than useless, everything being thoroughly soaked by this time."