If you want to quit without saving in Vim and have Vim return a non-zero exit code, you can use :cq
.
I use this all the time because I can't be bothered to pinky shift for !
. I often pipe things to Vim which don't need to be saved in a file. We also have an odd SVN wrapper at work which must be exited with a non-zero value in order to abort a checkin.