I have handled several, but don't own one (although I've made my own.) Two years ago I saw one built on an Official Police .38 frame, nickel plated, and in the original box with a factory letter. So far as I could tell it had never been fired. Asking price was $800.00. A nickel plated "Fitz" might have been unique.
The number made by Colt is in the low hundreds I believe, as they were a special order item and never cataloged. Most were made for law enforcement people who knew Fitzgerald personally. Perhaps the most famous one was owned by the late Col. Rex Applegate, who carried it during the time he was assigned to the White House Security Detail following Pearl Harbor in Dec. 1941. His was a .45, built on a New Service frame, but most of them were .38's
They were intended to be carried in a side-pocket - either a specially modified pocket or a holster. Some people take a dim view of cutting out the front of the trigger guard, but if you ever try drawing one from a pocket the light bulb in your head will go on. I have never heard of an "unexpected" discharge happening with one of these guns when they were carried properly. Then too, most of their owner's were very savvy gun handlers.
Then there's the old wives' story about the trigger getting blocked if the gun is dropped and the trigger guard is bent up. I suppose this could happen if the revolver was cocked, (which is most unlikely) but not when it’s in the forward position.
In terms of current guns, Smith & Wesson's don't lend themselves to this kind of conversion very well because of the location of the cylinder-stop spring. However Taurus revolvers don't have the spring in the same place and can easily be modified.