Great idea. If your competition gets his data from you, then you can leverage that position of power. First, you'll need to make sure you have the latest data. (If you're both updating with the Apple release cycle, then that will give you at least a week of lead time.) Second, a few booby traps in the data that your app knows to parse out will create angry customers for your competitor (after they wait or a bus that never comes) and you'll have "smoking gun" evidence that he's stealing your DB.