Hitting at what Mark mentioned about printing on shirts, if the logo has really large sections of print, when you're working, the sweat won't breathe through the logo.
Might sound nit-picky. But I remember "some place" I used to work and their logo didn't breathe very well and my back was sweaty on those one or two days I worked hard! If there is open space between the colors and letters, your workers will be happier!
love
nick