As for durability the Aspen is second to none. The big issue will be keeping it reasonably clean. To that end, I'd recommend wearing long underwear to bed whenever possible. Or, get a Design Salt Silk TravelSheet in the double-wide size ($100; www.designsalt.com). It's a bed/bag liner that you can use as a standalone blanket in very warm weather, and as a liner in cooler temps. And unlike the Aspen, it can be washed easily.
If you'd rather go with true individual bags, then there are still plenty of choices. You could get a pair of Feathered Friends' Kestrels (www.featheredfriends.com), 30-degree bags that come standard with a half-zipper but can be fitted with full zipper so they can be attached to one another. They're not cheap$265 a popbut as with the Western Mountaineering bag, the quality is top-notch. And at about two pounds per bag, they won't weigh you down.
Have a great trip! See you in a year, amigo.
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