STUPID idea. What's the advantage of it? Think about it. Concealed means CONCEALED and surprise is your greatest asset. If you have cause to flash a badge at a bad guy, you have cause to draw your weapon, and should have done so. If you show it, the BG is gonna draw HIS weapon and kill you dead before you can even get your hand on yours. On the legal side, showing that badge is walking a VERY fine line on impersonating a LEO.
Only Mall Ninjas carry them.