I wasn't too concerned with the half-zipper. I'm okay with the weight savings and I only ever zip my sleeping bag down about 2-3 ft to get inside anyways. If I'm too hot I'll just crawl out sleep ontop of it.

Question: How warm is 150g of 850 fill down?
http://www.ultralightoutdoorgear.co.uk/e...eping-bag-p1459

I'm also looking at this backless bag. Thoughts?