I've several extended trips planned this coming fall.. I'll be using a Tarp for shelter, combined with an eVent bivy.

I've not heard anyone yet claim wet/synthetics as a marketing myth..

On the other hand I've heard/known of many who claim they can and have climbed into a synthetic bag fully clothed and wet and woke up bone dry.. Have seen testament of hunters in Alaska who went with synthetics and had guides who were chilled, damp, and jealous wishing they'd left the down behind..

Yes my main focus is a bag that if need be I can climb into wet and have a better chance of surviving..