Carbons breaking has certainly not been my experience, glad to say. We don't usually hit hard objects with them though. The worst case for us would be deflecting one off the back of a lifesize deer target, you know the slap that makes aluminum shooters cringe, because they know that they just ruined an arrow.
I must add that my brother shot a buck this past season with an Easton Axis and the buck snapped the arrow off when it rolled to it's death. The break was clean as a whistle with no splinters whatsoever. I have always worried about carbon splinters in the meat. This eased my mind.