Wearing a vest sucks. Yes, body can save your life, and I will always wear one when in uniform. But they are still stiff, heavy, and hot. If you work in places like Texas and Florida, they can get blistering hot in the summer.
There have been a number of things done to try to make vest wear more tolerable. I think most officers are wearing some type of sports t-shirts that help wick away sweat. They help, but they are not miracle fabrics. Columbia Sportswear, however, may have a new product that could just be a God-send for anyone donning body armor.