One of the best ways that I've heard of for testing competing shell materials is to divide the material laterally down the middle--with one side Gore (for example) and the other eVent. I read that Patagonia did this once, and perhaps they still do. Of course, this would require considerable expertise in garment construction, but you would really be able to test the effectiveness of each material in a real world application.
I have several garments made with eVent (plus many more in all manners of Gore, H2No, Precip, etc.). So far, I think that eVent is excellent, but there are some limitations. First it is surprisingly not 100 percent windproof. Maybe that's OK for most people, but I want something windproof when skiing downhill at 30 mph at 0 degree F.
Second, I've found that the scrim on all the eVent stuff I have is much more prone to abrasion (from Velcro and other rough stuff) than the tricot used on garments made from Gore and H2No. Others have commented that the scrim can conceiveably be made from tougher material, but I haven't seen it yet.
Third, I haven't seen the eVent stuff from RAB in person, but all the rest of the jackets and pants in eVent are underwhelming (to me) in the fit and features department.
As for the breathability of eVent vs. Gore PacLite, my experience is rather similar to that of the Outdoors Magic test done some time ago--there isn't much practical difference: Outdoors Magic