My agency used to have a policy that required a special "qualification" for carry in any mode besides strong side OWB. Had to be shot annually, and the Field Office SAC had to sign a letter approving the duty use of the "alternate concealment holster." That policy fell off the books in 2014ish, and good riddance (huge PITA to run that 15-shot course - with every shooter having a different expiration date on the "approval" of their ACH).

I know a handful of folks who carry appendix in my agency, but it's a small group. Unfortunately, most of them are guys who just take their tiny striker fired personally owned weapons and put them in an Uncle Mikes or cheap suede clip holster and shove the pistol down the front of their pants...

But, then again, my agency still SPECIFICALLY prohibits RDS on handguns as "competition only" modifications. Interesting since we're likely going to getting the new MHS P320s off the Army contract, and IIRC, those are all set up to take RDS... Under three years to KMA date, can't wait.