I bought a pair of underwear and the long sleeve shirt. It's comfortable enough for sure. I used it the other day when it was about 93. I wet the sleeves and opened my cuff vents with all others closed. Not much happened, other than my forearms were a little cool. I finally realized that my upper sleeves might be velcroed too tight. Even after loosening the sleeves, and zipping my arm vents 3/4 of the way open, 90% of the cooling was on the arms. The rest of my body felt like it would be as cool or cooler with the vents open.
I suppose a better test would be to start out with dry arms and wet them later to get a feel for the difference.
What confuses me is the claim that your skin won't be wet. I kind of expected a Gore liner between the inner and outer layer of the shirtsleeves. Heck, they even tell you to pour the water INSIDE the sleeve. On their site, there was a demo showing a soaked sleeve and blotting the inside with a paper towel and not getting any water on a paper towel. That was not my experience. My arms were wet until the sleeves were dry - which was only about an hour - not four as claimed. Did I misunderstand their claims? I'm not sure that this performed better than any normal tech shirt with wet sleeves - or even some soaked sweat bands on your wrists.