I don't think Pro Shell uses a protein. Instead of a tricot knit lining, generaly made from 40 denier yarns, it uses a woven liner made from 15 denier yarns. It makes the lining lighter and more durable.
Your right in regards to the woven, rather than knit, 3rd liner of the ProShell. Thanks for the clarification. This liner does seem to be an advantage over the current tricot that's being used currently. However, the Gore membrane is the exact same as the XCR which means the breathability, when comparing just the membrane, is the same. This info I obtained from Alan DIxon of backpackinglight.com. Alan is considered one of the most respected authorities on w/b performance fabric in the outdoor industry and is not affiliated with any company.
At least for Windstopper, Im not sure this is the case. Put a windstopper laminate under a bubbler tester, and you will see that air bubbles right through it, at a comparable level as eVENT. And even Gore admits on its own Windstoppr site that it passes some air.
To be totally honest, I guessed on Windstopper hoping that someone would clarify it for me, so thanks <img src="/forums/images/graemlins/grin.gif" alt="" />. I assumed that all of the membranes Gore makes use a PU layer to which I acknowledge my mistake. I tried to do some research on Windstopper and couldn't find anything specifically on how it works. I did surmise that it probably doesn't include the PU membrane, but instead is meant not to be durably waterproof like the other Gore membranes, but maintain it's windproofness even if it is contaminated. Gore's website did say that it uses a hydrophobic 'coating' to keep external moisture from seeping through. However, once this membrane become contaminated with dirt and oil it will leak, thus it is considered only a water resistant and windproof membrane. You are right in saying that Windstopper most likely has the same breathability as the 1st generation Gore or similar to eVent. Windstopper should be in another category of laminates, not in the waterproof/breathable discussion. Thanks for the correction. <img src="/forums/images/graemlins/tongue.gif" alt="" />
Possibly, and surprisingly, there's a good possibilty that the pores from the Gore membranes are also covered with a hydrophobic and oleophobic coating just like eVENT. Why they would use both this coating and the PU-layer is unclear to me.
Though you would think that with as much time as Gore has had in figuring out how to get rid of the PU component from it's membrane, it hasn't. The fact is that it still uses it to fight the contamination issue. Until they figure out how to maintain the surface energy of the membrane without using PU, it will never be as breathable as eVent no matter what kind of marketing spin Gore uses.