I see only one POSSIBLE advantage of one of these things. If you clip it onto your belt next to your holster and someone happens to get a peek at your rig and also sees the badge, they might not freak and call the real cops. Of course, if you are doing it right they shouldn't see your rig. Any presentation of it as a police badge can get you into deep kimchee and a cop having a bad day might get unpleasant about it on general principles, especially if he doesn't like armed private citizens.

Generally speaking I vote NO.