Synthetic vs. Down Quilt for High Altitude

I hike in the Canadian rockies but conditions are similar. The answer is go with down. You rarely will have days without time to dry gear if neccessary and given the low humidity your gear shouldnt get damp. The weight savings in a 20F bag vs synthetic is substantial. I have never noticed a loss of loft in non winter in up to 1 week duration. Most through hikers use down as well.

Judging only by my experience, there shouldn't be a problem with using down. I've almost never has a problem with my down bag, and for years I've camped at altitudes similar to those you mention. The only time I've had any difficulties with condensation was when I camped in a narrow valley less than 200 feet from an active stream– and then the condensation was on my tent's fly. My bag was perfectly dry.

I agree that down is not perfect. However, down is still the best insulation if you know how to take care of it, and sleeping bags tend to be warmer than quilts. Most of the old 3- or 4-pound down bags are made with a pretty rugged outer shell, so you can manhandle it without fear. When I use my heaviest down bag overnight, I just try to get it opened up into some sunlight as soon as I can in the morning. After hanging it on a tree branch or rock, it is not unusual to see steam rising from it (from the sunlight). If I do that every morning long before it gets stuffed for transport, it stays good.

–B.G.–