After trying out countless synthetic bags and a few down bags, I finally purchased the 3.5 lb, Big Horn Super MF and have been very, very happy. After much reading, I decided I wanted to have the warmest, most breathable down bag I could find and this bag was it. I am a very cold sleeper by nature and have never, ever been cold in this bag so far. (Coldest temperature I have used it in is about -5 deg F in the Adirondacks). In very cold weather (less than zero F), I noticed the condensation freezing in the outer layers of the synthetic bags I tried. I haven't found that problem with the Big Horn. The shell fabric seems fine. If I'm in a leanto or other shelter where I might get wet, I sometimes bring a bivy with me (which bivy depends on conditions I expect). However in a tent it's just fine by itself.
I'm sure any sleeping bag you listed is an excellent product, for me the deciding factor was the shell fabric. I wanted something breathable and would manage the water/weather proofness by using different methods (kind of like layering).
This has been my experience with the Big Horn, of course YMMV. I don't work for any outdoor retailers, just a very satisfied customer. I'm now looking at getting their meltdown jacket.