When these first came out I purchased some to give 'em a try and in subsequent threads some of these same issues came up. Now breathability may vary depending upon your local, but I found them to be adequate for the tropical PNW, certainly much better than a Goretex or Event garment but less than a cotten T. This assessment is based on the absence of perspiration running down my torso while hiking up a long stretch; however, it was definitely humid feeling inside the Thorofares, but the exterior of the fabric was dry. To me that pretty much confirms that the fabric is breathable. In short, pretty much what you'ld get with a windshirt, but with the added convenience of being able to unbutton all the way down, something my Golite Wisp can't do (to bad the pants don't have a vent). And as others commented on the thread, the fabric seemed pretty much the same as what you'ld see in a windshirt. So, if it looks like a windshirt, and works like a windshirt, it must be a wind shirt (and pants). Just as a windshirt is not raingear, doesn't insulate and isn't modest (both my Wisp and Houdini can be seen through), yet are functional pieces of one's kit, so too are the Thorofares. As for the latter, I don't wear thongs or briefs, but rather, boxers, the real ones that go half way to my knees. I have running shorts that are less than half that length with slits up the side, so no problem.
What seems to be missing from this discussion is a look at the origination of the Thorofares. They take their name from a region in Yellowstone that's notorious for extraordinary mosquitoe hatches. So if any of you need lightweight bug protection, these offer sterling performance in that regard. No kidding, they march around all over the fabric trying to punch through like Republicans drilling for oil, and they just CAN'T. And no permitherins required.
Anyways, to return to the topic, if the beige pants seem too transpaarent, well, exchange them for the brown ones