In any event, in four cases out of five I will opt for a down bag over anything else. Down bags do cost more than comparable-temp synthetics, sometimes by a ratio of three to one. But that is made up for in part because a down bag will last longer—usually by the same ratio. So in terms of dollars-per-night, it's a wash. Beyond that, in almost all cases down bags are more comfortable (they're softer and drape better), lighter, and more compressible than a synthetic of equal temp rating.
Take the case of your late, lamented Cat's Meow ($159; www.thenorthface.com), a 20-degree synthetic bag that uses Polarguard Delta insulation and weighs two pounds 12 ounces in a regular size. Western Mountaineering's AlpinLite, on the other hand, is also rated to 20 degrees, but weighs a mere one pound 15 ounces, and packs down to about half what the Cat's Meow can manage. Of course, you pay for these advantages: the AlpinLite sells for $325 (www.westernmountaineering.com). Or you can get a Marmot Helium—a 900-fill bag rated to 15 degrees—that still weighs only one pound 13 ounces. Price: $359 (www.marmot.com). Finally, Feathered Friends' 20-degree Swallow may be the best buy of all. Made with light nylon shell material, it weighs a mere one pound 11 ounces and costs a not-unreasonable $270 (www.featheredfriends.com).
The knock on down, of course, is that it loses loft when wet. Which is true. But you have to soak a bag pretty thoroughly for that to happen. And all the bags I mention above have shell treatments that go a long way toward shedding the little drips and drops that will get into a tent. I've been using down bags for many, many years in the wet Pacific Northwest, and cannot recall a time when I felt my down bag had become so wet that it was useless.
Good luck once you get to Nepal!
More kayaks reviewed in Outside's 2004 Buyer's Guide.