I've experienced the condensation issue with a down sleeping bag, on a 7 day hike across the Bailey Range in the Olympics, through alot of rain and humidity I picked up probably 4 pounds of condensation in a ~4 lb down bag. And I was definitely sleeping colder at the end of that trip than I was at the beginning, too. Still, the best solution to 'de-condensating' the bag was alot of airing out, and a few overnighters in the much drier and warmer Eastern Washington. I don't think that bag suffered any permanent ill effects, like down clumping or loss of insulation value.