I use both clips and clipless. I like clips just to get to my classes. I don't want to be that ****** with mountain shoes clacking around walking down the halls. My Adidas Hammers with crank brothers cleats sound obnoxious walking down an echo-y hallway, and any decent mtn shoe will too.

But clipless is the way to go. If you can fit a pair of shoes in your bag with all your other stuff, then it's completely understandable.