Thanks to everyone so far for all the great info. Western Mountaineering is definitely one of the best down bag manufacturers out there. I'm just not sure if I want to spend that much money on a sleeping bag right now.

If only I worked for Moosejaw! <img src="/forums/images/graemlins/grin.gif" alt="" /> (they are able to get a discount on the bag)

I'm now strongly considering the REI Sub Kilo. It weighs about the same as the WM Ultralite but the stuff sack is a bit larger. I wonder if I can compress it down to about the same size as the WM Ultralite.

What size sack comes with the WM Ultralite? Can it be packed any smaller than that?