Some one told me to always have the words on the front. Then you are warned if someone is going to hit you. Nothing worse than being attacked from behind.
I think this like the toilet tissue issue. Let it hang in the front or back.
I go with the words in the front because I often wear a shirt or sweater over the shirt.
It will be interesting to see how people react.
Chicks have different considerations. People might not want to read something long for fear they look like they are staring at breasts.
A small woman might get away with something on the back—it would take a real cad to hit her.