Hi, OM: just got a 2-hour test of the Pertex. A group of us planned a rain-or-shine day hike. Naturally, we ended up choosing the "rain" option. Just as we began the hike (in a typical midwestern woods, fairly mature, with one short stretch of old-growth), the sky opened up and we got one of those big-drop, full-on, buckets-of-rain downpours that lasted about an hour; after that it changed to a normal rain storm that stopped about 15 minutes before we got back to the trailhead; temperatures were in the mid-70s, and humidity remained high (75%, I'd guess.) I wore the Pertex jacket and pants throughout, over nylon shorts and a synthetic t-shirt. I was carrying an Osprey Exos 48 pack (trampoline suspension, so well-ventilated.)
The results are mixed, and tend to support someone's earlier assertion that you should consider it more of a soft-shell than a full-on rainsuit.
I'm not convinced that the rainsuit actually leaked. My clothing was not soaked, but I noticed dampness on the shoulders of my T-shirt (where the pack straps came around)and the abdomen, and a little on the upper back (again, where the pack actually touched the T-shirt. However, on a hot muggy day, without a jacket, my T-shirt gets wet in all those places from perspiration. It was about the same amount of dampness as I get from perspiration, so I can't say that it leaked with any certainty.
However, when I held the jacket up and examined it, I noticed that there was liquid (drops, not soaking wet) on the inside in a few places, and that it corresponded to the shapes and locations where the fabric had wetted out. Again, all of those patterns pretty well coincided with the normal perspiration patterns, so I can't conclusively say whether it leaked.
My shorts and legs remained dry, except for a small amount of perspiration on my legs (again, normal for a hot, humid day.) I did not notice the patterns of liquid on the inside of the pants.
The rain jacket and pants dried pretty quickly; I had them spread out in the cargo area of my Honda CRV on the 20-minute drive home, and they were about 75% dry by the time I pulled into the garage.
I'll keep my eyes open for another drenching downpour, all in the name of science
Maybe I'll just walk around the neighborhood, no pack, and see if the same wet patches appear. (If they don't, it may mean that it is just perspiration that can't escape where the pack belt, straps, and suspension block the fabric pores.