If one of your objectives in selecting a windshirt is eliminating moisture vapor, your selection should rely more heavily on Moisture Vapor Transmission Rate (MVTR) than Air Permeability Measurements (APM / CFM).
A high MVTR waterproof-breathable shell jacket may be the holy grail that can replace both a wind shirt and a rain jacket. Do they exist, and where do we find them?
In this article, we make the case for spending some extra weight on rain jackets and rain pants that offer more ventilation features (and durability) than typical ultralight rainwear styles.
The Helly Hansen Odin Minimalist 2.0 jacket (180 g / 6.35 oz, $220) is a lightweight 2.5-layer rain jacket with a well-designed hood and minimal features.