I tried a t-shirt and just my pants once, for 10 minutes. Can't stand it, I feel like weird and naked.
I personally like having a fighter mesh chassis with some protection which is definitely better than nothing, I would like to see more peeps rocking those jackets then going squid.
Oh oh oh, I actually fell a week back and was so happy I had my jeans with knee protectors and jacket. Came out a little shaken, with a tiny tiny road rash but if it where we friends wearing Jordans shorts. Whole different story. I was even super lucky to have my backpack on since that broke the fall and even prevented my back from riding cement.