My suggestion is to wear something that is comfortable and breaths.....that wicks the moisture away from your skin as you ride, and don't worry about 'performance'. I'm a bit older so shaving 1/1000th of a second off my time on a ride of 20 miles for 1hr 15mins. by what I wear is really not important to me.
Comfort during that 1hr 15mis. is.
I've been wearing some old bar room baseball shirts (nice light spandex material) for years and love them.
Last year I asked the LBS if they would be getting any replica Yellow jerseys from the Tour that Armstrong won, mainly because I thought it would be his last one and wanted to wear one because I was proud of his accomplishment. To make a long story short, they never did get them in and so again this year it's the old baseball shirts and I'm fine with that.

Len