I've been think about this for a while. I just bought a western mountaineering bag (megalite) a few moths back and was considereing to use it as top quilt and bag for my hammock during my thru-hike in 07. I had been muling around the Idea of buying a no sniveller quilt from JRB as a second underquilt for those really cold nights. (also a gossamer gear 1/4 wide/long pads on the way, so I'm not sure about the N/S). I have used my Megalite down to the mid to low 30s with good results, so my question is, should I Invest in a lower rated bag than 30 degree or will I be alright. (for those shelter nights I was planning to use my nest and bag for warmth). Thanks all