I saw one demonstrated several years ago. They were very expensive, and I didn't see where it improved shooting very much at all over simply marking your ramrod and loading to the mark. The man demonstrating it had some relationship with the company, and was pushing his product to percussion and those zip gun shooters. I was demonstrating flintlocks, and he wanted nothing to do with me. I don't advocate compacting powder in flintlocks, so I had no interest in the Kadooty, either. He had never fired a flintlock, and seemed impressed the the gun fired, " kBOOM! ", with no delay. He seemed amazed that I hit the small target, too! Obviously, I was doing nothing for his sales, so he distanced himself from me. I was at the show primarily to demonstrate tracking, and track identification, so I spent the rest of my day doing that.
LIke some of the other posters here, I too have noticed an ABSENSE of this device from the firing lines at Friendship at the NMLRA Spring and Fall shoots. Its no longer being made, or at least I can't find the manufacturer anymore. I would think the market place has spoken. There are betting things you can do with your money.