This is a comparison review of this Aegismax mummy bag with the Naturehike rectangular down bag.Over the past year my partner and I have upgraded a few bits of our camping gear. Getting well-made, compact, and lightweight sleeping bags were on the list. We have pretty decent synthetic-fill summer-weight bags from a major brand, that have about 5yrs of use. Going to down-fill was the obvious path, and recent offerings on Amazon have shown that good-quality down products are available from smaller manufacturers at lower prices than the outdoor equipment market has seen before.My wife wanted lots of foot room and a full dual-slider zipper to poke her feet out if it is warm. Naturehike's rectangular bag has met her needs very well this summer. The penalty for the roomy rectangle is about 4oz (compared to the Aegismax mummy) which is very reasonable. They could reduce the weight by at least an ounce if they put a light-weight zipper on it; instead they used a full-size YKK zip that will be reliable for years, without needing the light-touch that much ultralight gear requires. It is warm and cozy, with a cinch cord to draw the top opening together if it is particularly chilly. The advertised temperature limits seem to be reliable guidance. And the glossy water-repellant finish on the outside of the bag should help deep the down dry in the event the sleeper presses up against a tent wall damp with condensation. The compression stuff sack is made from a heavier nylon that will stand up to regular use.I have found mummy bags to work fine for me, so I purchased an Aegismax (size large, I'm 6'/175#) last year and really like it as a integral part of my ultra-light 3-season kit. Compared to the Naturehike, the shell fabric is finer, almost gossamer, but the tight thread count keeps down from poking out. However, I do seem to find a feather or 2 loose about the tent each morning; I don't know how they get out, but they are coming from my bag somewhere. Pulling the mummy hood around my face works well to maximize heat retention, but I have yet to have it out in the 40s to need it. True to ultralight design priorities, the zipper stops mid thigh, so getting in and out requires a bit more movement. And the zipper is well-made but rather light; I have to slide it more gently and slowly, being a little careful to not catch the bag fabric. The compression stuff sack is made from the same fabric as the bag shell, which is perfectly adequate but requires a bit more care in handling.Going to down-fill bags has reduced our sleeping gear volume by 1/2, and reduced the weight by 1/3. These 2 bags have met each of our priorities very well, and we wouldn't change our purchases. You can tell in the comparison photo that the Aegismax is more compact, in proportion to the weight savings. Cinching down on the compression straps makes them both even smaller! But if size/weight are not the priority for you, maybe some extra creature comforts will guide your decision. Either way, you can sleep cozy!