Ghost sights are a compromise, at best, and best used for hunting and quick shots.
SRH
I do believe I said the ghost ring sight is best for hunting for use on running game or in lower light conditions. A very small target aperture may be totally useless under those conditions. This contraption the end of a top lever is even more of a compromise than a well designed ghost ring, but certainly could give more precise sighting than simply pointing a front bead when hunting at modest ranges with slugs or buckshot. It is an interesting variation, but I don't think it will ever put Lyman out of business. You are certainly correct that there is a point where an aperture becomes too large to provide a focusing of light rays.
