Actually, let me in on this. I did a lot of looking in to this very subject.

PV has a better evaporation rate than wool does. So when you are hot and sweaty, the increased evaporation rate should (At least in theory) keep you cooler than wool.
KW, I'd be curious to see your source(s) on this statement. Where did you come across this information? I'd love to read them.

I've worn wool in the summertime for 15 years now in various forms of historical reenacting, as well as my kilt. It is been my observation that all of the tourists watching us in their synthetic tank-tops, shorts, etc. who thought we were all crazy and viewed themselves as "cooler" were actually sweating more & far more uncomfortable than we were.

The problem: AC. We have become so used to air-conditioning that we can't stand the heat anymore. My Dad remembers summer in Arizona without AC, folks today couldn't take that.

My money is on wool, linen or cotton -- natural fibers -- over man-made stuff any day.

T.