I not only prefer "or", I have gone as far as coercing coworkers to use it as well, for the simple reason that "or" always works as expected in this type of statement. I'm a strong believer in Defensive Programming, and avoiding "debugging hell" at all costs. I honestly don't think that the lesson in this case is worth the potential time waste. This is only my opinion, I am definitely not telling anyone else here what to do.