I anticipated condensation in my vest with sleeves, so I attached the sleeves only at the top of the vest... so I would have completely open arm pits. Also, I did not wear it against my skin. A week ago I first used the vest sitting in the cold rain. This weekend, I was in cold, dry weather. Friday night, hiking in the cold, when I got overheated I did not notice any condensation. Still, I would expect it, and would make any garment with good venting so you don't overheat.
I was never aware of any dampness, coolness or discomfort of any kind while wearing the vest. It was surprising how it was like it wasn't there, no clamminess, no cold spots, just even warmth. When I took the vest off, the cold hit me immediately.