[IAmBroom]

> The crucial thing is that Gore-Tex is water vapor permeable.

While dry, or intermittently wettened (so it can still shed water). Numerous independent tests show that it doesn't breathe at all, once the surface is fully wet. Also, Gore-Tex is no longer best-in-class amongst rain-shedding breathable fabrics; it simply has name recognition.

To be fair, few things do breathe once their surface wets... but wool's surface is so convoluted by the twisty, hydrophobic threads that it rarely gets fully wet on the surface.