Yes, a couple times. Though none were a case of me utilizing SchH training in real life to activate the dog to a potential threat. In all cases the dogs activated on his/her own in response to the threat, as any good GSD trained or not should do. Though admitedly training for that sort of alert barking does make it come more naturally and confidently to the dog. The SchH training mainly gave me control in a situation where without that level of training I might not have had it. And in one case the dog knowing that a hold and bark will do when the guy freezes and stands still, and there's no need to bite right off the bat, probably saved a messy dog bite situation (even though it turned out later that guy deserved that and worse).
That's the extent to which I've used any of their protection training in real life simply because I've never really needed to. Now obedience is used frequently, and on a few occasions the formal SchH obedience has been used for the purpose of intimidating suspicious people. People see a dog responding that way to the nifty sounding German commands and they assume the dog can do more, making it an even better deterrent.
And one time Kaiser somehow extrapolated SchH article searches to finding my old college class ring that had been lost in the yard months before, and telling me exactly where it was and making sure I came over to get it. No idea how he made that leap, but was greatful he did.