Section hike - low temps to expect?

[grrickar]

I am hiking with a group from Davenport Gap to Hot Springs this week. It looks like the temps are going to be lows in the 40s, but I suspect they may be lower in the mountains. I have a lightweight down bag, but it is only rated to 45 degrees. I have a coolmax liner that allegedly adds 8 degrees, so that would get me down to 37 degrees. I will be staying in a MSR Hubba, which is small but drafty if the wind is up.

So my question is what should I take: the down bag with is rated to 45 degrees or the synthetic (heavier) bag rated down to zero? I'm thinking I can sleep in long johns if needed and save on the weight of the bag (not to mention it is 3-4x larger than the down bag, even compressed.

[grrickar]

I took the 0 degree bag, and very thankful I did. It was synthetic, and the bag got wet on Friday night from a leaky tent I was sharing with a buddy. Then on Sunday morning it was 26 degrees at Brown Gap and all the raid had frozen (as would I have if I had been in a 45 degree wet down bag).

We got rained and blown around a good bit on Friday night, and rained and hailed on Saturday hiking into Brown Gap. Most everyone gear was wet - mine only slightly damp.