I'm looking for feed back from those of you who are using the treated down sleeping bags; how do you like them, and how do they hold up after say a week or so in the mountains?

I'm looking for a new bag and really interested in the Sierra Designs Back Country Bed with their Dri-Down. I was able to try one out for a night and I liked the design of it. I'm just curious how the newer treated down stuff does after a week or two in the mountains. The reason I ask is because i'll be going on a Sheep hunt in mid-August and would like to know if it's worth giving a try?