I know one of the benefits of having a PU component is in the lamination and taping processes. Because PU adheres so well to the adhesive, Gore most likely thinks that the sacrifice in breathability is made up for in its durability. We discussed this at length at our Westcomb sales meeting. The explanation I got from the material engineers is that instead of relying on the PU layer for lamination (which makes building a Goretex jacket much easier), Westcomb actually forces the glue through the pores of the membrane (again 80% of the ePTFE membrane is air) at a much higher pressure than is needed for Goretex allowing for the tape to adhere to the face material.
This indeed sounds very logic to me. In fact, I think it's the same way Gore solved delamination problems they had by forcing the PU layer partly inside the PTFE-layer
The supercritical gas based production method is indeed a very cool thing (literaly <img src="/forums/images/graemlins/wink.gif" alt="" /> ). Perhaps the coolest feature is what I would call the self-healing property it adds to the membrane.
I've taken a look to Westcomb but currently the main problem is it's very hard to get any detailed information abou them. Their products are hard to find. I received their 08 catalog but it doesn't explain enough what makes them so different. Now, if they would add pit zips to their lighter jackets, that would be something.