"However, my concern with sleeping with down clothing on especially with Bivy is your sweat wetting out down clothes thereby making them less insulative when needed around camp. If you are in humid weather, of which I am, I think this could be problem in morning before it has time to dry out.
Has anyone else had a probnlem with body produced condensation in down clothes while sleeping?"
I should have added that I *always* use a VBL layer over my long underwear while in camp. Always. It stops perspiration caused by the dry winter air, and keeps the insulating layers around you from getting soaked. It doesn't make that much of a difference over a single night, but the longer you're out the more important it is to use a VBL.
Personally, I'm unable to use a VBL during the day, but YMMV.