Yeah, I'm with you on the sweat.

I wear a very light Icebreaker wool top -- short sleeve in the summer and long sleeve in cool weather. If it's chilly and windy, I add a 3-oz windshirt on top.

The nice thing about wool is that it reduces the thermal shock of stopping for a break with a wet top. I always got chilled when I wore synthetics, but wool has eliminated that issue. The other nice thing is that wool doesn't ever get the hiker stink. I wore my s/s top last weekend on a very warm hike in NC. I could have wrung the sweat out of my shirt. And it never started to stink.