Good spot, Rae.
It makes sense - it's like going back to school biology and doing semi-permeable membranes(!):
- moisture will only pass from the high concentration to the lower concentration
However, buying something with Gore-Tex is a bit like buying a BMW Yamaha: you can be reasonably sure of getting a quality product. You can also be sure of paying extra. That bit is like BMW.
I only have two items of Gore-Tex: motorbike boots and a coat:
The boots don't get particularly sweaty in the dry or wet (Alpinestars ones). Tick.
The coat - not so convincing, since you tend to just waft moisture out of vents, neck, etc. But it is definitely waterproof.