Marmot Atom Sleeping Bag REVIEW

Since the Atom has a partial zipper vs. the Western Mountaineering Summerlite, the Summerlite is fully baffled vs Atom's sewn through construction, and the two bags have about the same loft I wonder where the weight difference is? Is it the Atom's fabric or a lower grade down?

Don's measurements of the Marmot Atom and the Western Mountaineerig Summerlite:

Atom:
weight advertised: 1lb 4oz
weight measured: 1lb 6.6oz
loft (single layer shoulder & hip): 1.9 in
loft (above footbox): 16 in
fabric: Pertex Quantum N-090 ripstop shell Pertex Quantum N-090 taffeta lining

Summerlite:
weight advertised: 1lb 3oz
weight measured: 1lb 5.4oz
loft (single layer): 2.1 in
loft (double layer shoulder & hip): 4.1 in
loft (above footbox): 16 in
fabric: 0.9 oz/yd2 (31 g/m2) Extremelite 20D nylon shell

Summerlite Review:
http://www.backpackinglight.com/cgi-bin/backpackinglight/western_mountaineering_summerlite_sleeping_bag_review.html

This is a great sleeping bag… it is what it is… a sewn-through down bag. That means it is less expensive and has limitations. The extra weight is a disappointment. I'll weight mine and post the results.

Earlier, Steve asked why, with the extra features (full zip, baffles, etc.), the WM Summerlite weighed less than the Atom. The shell material and down (quality and/or quantity) could be part of it, but the cut of the bag could also be a culprit.

Reading the specs, it appears that the WM is a slimmer fit than the Atom. I don't own either the Atom or Summerlite bag, but I know from crawling into the Marmot Hydrogen and Helium in the shop that they are roomier than most of the comparable WM bags. I prefer the WM bags to the Marmot, if they fit; if they didn't, Marmot would be my first alternate. (For what it's worth, I ended up with the WM Mitylite and Megalite; the other bags I tried in the Extremelite series were cut too tight for me.)

As I own an Atom, I think the review here on BPL is right on.

However, my email concerning this article contained the following description:

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Marmot Atom Sleeping Bag REVIEW

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I eagerly clicked the link to read how the author used the Atom for winter trips, and I really don't see this type of information contained in the article.

For the record (since it is a complaint of mine, too, but my Helium suffers the same weight difference from the published weight), my Atom is 18.5 oz for the regular length.