I've had my LT3, I think it is, since around 1989 and it's seen a lot of hiking and river miles, in that time. I've tried to dye it dark brown, a couple of times,(they used to make a chocolate color) to hide the sweat stains, to no avail, but it's still in good working shape. I recently discovered that "Shout It Out Gel" gets the sweat stains out, ha ha, should have done that twenty years ago.
As far as keeping your head cool in the summer goes, well most all hats are going to be warm, but not as warm as the sun beating down on your head. I just get the inside wet, when it's real hot in the desert and that seems to work for me, even when I had a full head of hair. I tried on the Air Flo model and didn't like it, as well as everything, from a Seattle Sombrero to a Panama Jack and the only one I still have is my stinky old Tilly.