Which Rib Protector do you actually run?

Before I throw money at another piece of kit I need to know if a rib protector is even worth buying new. I'd rather hunt a used one in good condition than pay extra for something that just looks newer. If you actually run one, is the extra spend doing anything once it fits or is that just a logo. A cheap one that doesn't sit right is wasted money, that is the part I keep coming back to.