I work as a NOLS instructor and thus demand a lot of my gear. I brought the MH phantom 0 on a 24 day backpacking and climbing expedition into the Wind River Mountains of Wyoming in September 2011. The bag kept me warm and comfortable during the month long trek despite the variable fall weather in the mountains. I appreciate the lightweight no frills design. The bag has everything I need and nothing I don't. I also appreciate the durability. The bag retained it's feathers and thus it's loft very well, especially when compared to down bags I've owned in the past.
Size note: I am 6'1" and figured I'd save a few ounces off my back by squeezing into a regular size bag. I fit into it, but just barely. In the future I will buy a long.
I abused this bag in conditions it was designed for and it performed just as expected. After a soaking ascent of Mt Madison I hopped into this bag which stayed dry in its nice little stuff sack. Temps dropped to ~8 degrees outside the tent with winds around 35 mph gusting higher. I was very comfortable in this bag. Humidity in the tent was outrageous the outside of this bag got damp as expected and I was still very comfortable. I was able to dry out things by sleeping with them next to me in the bag and keep my boot inners warm at the bottom of the bag with plenty of room ( 5'10'', 140 lbs). Pulled it out the next night shelter after traversing and the loft came right back after being put away damp. With 8 guys in this shelter and stoves running humidity was insane again. Bag got damp again overnight but stayed very warm. Bottom Line: Super light weight, Dries fast, Very Warm
this bags weighs nothing! i haven't extended camped in real cold with it yet, but it was great on a recent overnight in the car with temps in the teens. i am 5'9" and feel like I am nearly at the limit of this bag when i am tucked into the hood...i'd suggest bumping up to a long for anyone taller, especially if you plan to sleep with layers inside.
i've only used this one time so far but it performed as stated. temps were about 14 degress with snow, i was sleeping pretty much in the open and with light snow coming down. i was super warm all night in a base layer and had a dusting of unmelted snow on top of the bag in the morning which attest to its insulating ability. Great bag!
I don't necessarily need to push this bag to it's limit, and I don't. I do however love being out on long climbing trips where I know that slipping into the bag at night is going to be great. Super warm, I wish it came in a short model but other than that it's great.