Depends on how you sleep! As a child I learned to take my sleeping bag with me when I turn over (which I do a lot of). If I used the Big Agnes setup, I'd end up sleeping on the ground with the pad on top!

A lot of people do use down bags in the humid east, and do quite well with them. I wouldn't rule out down--it's a lot lighter, lasts 2-3 times longer and takes up a lot less space in your pack. You do have to be a little more careful to keep it dry, but it's a myth that synthetic bags are warm when wet. My own experience is that NO insulation is warm when wet!