My BCUK Ventile has double on the shoulders and upper chest, and single everywhere else. The wet through has happened on the arms, and hood, but I can't recall actually getting wet through the double layer. Cold, yes, wet, ummmm, don't think so. If I wear fleece, or good wool, it isn't too bad, but long sleeve cotton shirts, not good. Yeah, I know "cotton kills on the hills" but I don't wear this thing on the hills. I wear it to work, and around town, and for day trip outings.
I have worn it for walking in winter weather and it is great when it is cold and dry, very comfortable. The two experiences that have put me off wearing it somewhat were cold, wet, winter days when I was doing a fair bit of walking in the weather. There was no happy medium, I either wore a pull-over to separate me from the cold Ventile, and sweated up a storm, or I went with just base layer and had to put up with feeling cold and damp. Also, I found that having the damp fabric zipped up around my face got cold too.
I once wore a cotton coat (not ventile) over a worn Polartec 200 fleece at a hammerin, so not out in the wild, just wet and breezy, and near on froze my nuts off, it was like wearing a refrigerator!