I just got home from a week in deep South Texas (like right on the border deep) and, with one exception, EVERY SINGLE LEO I saw had their firearm in a Serpa holster. This was mostly BP officers, but also plenty of local law enforcement in plainclothes who were working security at the ranch entrances. The one exception was a holster similar to the Galco Quick Slide, but with fancy BBQ-type design engraved/tooled/burned into it.
I guess the word still isn't out in some places yet.