Heck, OM, the test is half done already!
I've used the GoreTex rain suit (an OR Foray model) for about 5 years, with results pretty much like you'd expect. It keeps the rain out, even if the outer fabric wets out (which it does.) I've hiked in it during some hour-long downpours, and any number of day-long drizzles interrupted by heavy rain ("Yeah, it rained all weekend, but at least it was muddy...") Of course, keeping the rain out is something different than keeping me dry: as with any rain gear (breathable or not), if you move around a lot while wearing it, moisture from condensation/perspiration will build up. (It can't escape as fast as it builds up, even with the excellent pit zips and leg zips, in addition to the GoreTex fabric, in the Foray.) But the performance of my outfit was better than any other waterproof-breathable fabric I'd used (which included Marmot's Precip and Patagonia's H2No.) In fact, it came very close to the performance of a poncho with a cord tied around the waist to prevent the wind sail effect. The GoreTex provided a bit of extra warmth in colder temps, too, when I would use it as a light shell over long underwear in clear weather. The pants and jacket show no wear or indications of abrasion whatsoever. Overall evaluation: I'd gladly continue to use unless there is something a pound lighter that performs as well or better.
Enter Pertex: a pound lighter and a claim that it's better. (My version: the OR Helium 2 jacket and Helium pants.) So far, I've worn it in 3 all-day drizzles with periods of light showers. It has proven to keep that kind of rain out just as well as the GoreTex, with the same amount of wetting out (but no leakage.) There has been significantly less dampness due to perspiration/condensation - but so far, it's all been spring weather, no hot summer. I've also used it once on a cold day, over a down vest, as a shell when hiking; it had rained the day before, but didn't rain the day we started. It's performed flawlessly, so far. My main concerns are whether it will leak in prolonged heavy rain, and whether the lighter fabric will abrade and wear out quickly. I am realistic enough that, being a lighter fabric, I don't expect to get five years of performance out of it; however, it costs about a third what the Foray cost, so if I have to replace it every third year, I'm still money ahead.
So, I'll continue to test it this year and into next spring, and see how things go. I'm really hoping it will play out well. It's comfortable to wear, takes up very little space, and appears to be functional.