I am in the market for a 3 season bag to replace my current Sierra Designs bag that is over 20 years old (still looks great btw, really says something about the quality). I was excited when I found the Nitro UL 20. 800 down fill on sale was a price that was hard to beat! Unfortunately, I was a little disappointed when the bag arrived for a handful of reasons.
I ordered the regular length which is recommended for a person up to 6' tall. I am technically 6'1" so the regular length was a gamble, but I don't like sizing up to long unisex sizes (for 6'6") because I worry about being able to heat up the extra space in the bag. I am a slim 155lbs and run cold when I sleep. For reference, I fit into the Marmot Phase 30 bag (unisex regular length) and the Marmot Ouray (women long) and the Big Agnes Skeeter 25 (men's regular) comfortably. The Nitro UL runs very short. My feet and head were smashed in when zippered up. I had my Dad who is an even 6' tall and my friend who is 5'10" both try to bag. They each said that the bag seemed short. It also seemed to run quite narrow. The spoon-shaped design is supposed to be a little roomy, but this was actually much more narrow than my old SD bag and my Marmot Ouray.
Even though the baffles are 5" wide I noticed huge gaps in the down when held up the light. The down fill shifts very easily in the baffles, which makes me wonder if the fill weight was shorted or perhaps the baffles should be smaller to keep the down from shifting so easily. It was easy to shake the bag out to reposition the down. But this might be problematic in the backcountry, leaving a person with cold spots and drafts.
3. Fabric and features:
Although the 15D nylon felt very durable, it also felt quite cheap and papery. It did not give the impression that it would do a great job at repelling water (frost or condensation, etc). You can feel that it will do a good job standing up to abrasion from the occasional cowboy camp, but it did not seem particularly comfortable. The half zipper was very smooth and seemed durable. There was zero snagging when zipping the bag up or down. Lastly, the venting foot box is a neat feature that compensates for the half zipper nicely, but there is still room for improvement. With the narrow shape and feel of the bag, it was a bit difficult to bend my leg enough to get my feet out of the vent. Once my feet were out they didn't have much wiggle room. Adding just an inch or two to the width of the bag would make a huge improvement in overall comfort and ease of use.
Overall, I can see the Sierra Designs team really put a lot of thought into the design of this bag. It targets the budget conscious through hiker as well as the gram counting alpinist. The features nicely intersect between quality, cost efficiency, weight, and packability. I was impressed by the bags ability to squeeze down to half the volume of the included stuff sack. This is a good budget alternative to a Hyperlite, Feathered Friends, or Western Mountaineering bag and will likely last a person many years with proper care. But overall, I made the decision to go for a Marmot bag due to fit and my personal preferences.