My commute is flat 11kms each way.
I commute during warmer days using cotton polo shirts and I manage to get there with very little sweat, and I've asked my wife at the end of the day to check my odours and I didn't smell and nobody at work has complained.
On cold days I usually change the upper clothes.
I would like some sort of rain pants because although I have fenders, I've had to get back home during rain, and there's too much water splashing from the front wheel. Luckily it hasn't happened on the way to work.
Commuting by bike isn't very common in Portugal so I don't have the courage to show at work with cycling specific garments. I'm already considered completely nuts for biking.
So Pertex or Windstopper won't hold an half an hour rain?