I've used eVENT and Gortex (paclite and XCR) in many environments with both bivvies and clothing. I have never had a durability issue with eVENT but have with Gprtax Paclite. However it is important to know that 3ply eVENT (used by Integral Designs for example) is much more durable than 2 ply with the exposed membrane. It is also heavier.

Not that Jason is a super guy but he is a representative of several outdoor brands, all of which, I believe, employ Gortex and not eVENT. I have found eVENT to be the best combination of durability, waterproofness, and breathability. The difference in breathability between any of the Gortex line and 3 ply eVENT is pretty extreme and immediately noticeable. I have used eVENT bivvies in constant, hard, 5 hour rain without so much as a drop of condensation. I can't sayt he same about Gortex.