The amount of moisture from condensation will never impact these bags. The outer layer is too heavily treated. The review from outdoorgear lab notes that the Western Mountaineering Kodiak will be fine unless you are sleeping in a couple inches of water. I've woken up with the water beading all over the top of my bag and dripping on it from the walls of the tent. It didn't lose any loft. There are certainly down options that would be affected by this, but most of the top end down bags won't be, especially if it is treated down.

However, for survival long term and in conditions where it might rain, the option you mentioned is almost certainly better (unless you have to carry that thing far).