Interesting.
I get that if it's warm, but goes chilly when it rains, that would suck, but ive used cheap packaway jackets and theyve been quite breathable. The base layer seems to be more important. Goretex certainly isnt as breathable as they make out anyway. Waterproof AND truly breathable just doesn't really happen in reality I think.
Chafing. A t-shirt shouldn't take long to dry if its good material and it's hot and the water evaporation would cool u down.
When out couple weeks ago, it was very hot and we came across a spring. I soaked myself on purpose, it was lovely.