Good suggestion 44 AMP. If ghost ring sights were the "answer" to revolver sighting problems, we'd see them on the range. Having shot Hi-Power for some time...I'm 63 now and shot my first match in '65, I can tell you that a peep sight is useful only if it's close to your eye. You can judge this for yourself by sighting through the peep on a 1903's ladder sight and then trying one on a 1903-A3 or M1 Garand. On the 03, the sight is a foot or so from your eye and you have to go find it. On the A3 and Garand, it's not even very visible unless you concentrate trying to see it...the point of a peep sight is seeing through it and concentrating on the front sight...that's one of the reasons the Garand was such a good battle rifle...the excellent quick duty rear sight.
On a revolver at arms length, you have to go find the peep (ghost Ring) then the front sight...Unless that peep is pretty big, it's not going to be easy. And if big enough, the sighting errors would be enormous. It would slow down the sighting process on a weapon designed for quick last minute work....
Pistols, and revolvers...were designed to be shot with one hand, off horseback or up close on foot as last ditch weapons, better than a sword, or bayonet but distinctly inferior to a rifle or carbine if the distance was anything over 25 yds, just to be arbitrary, You could argue for 50 yds and maybe get some takers. That they can be effective, handguns that is, at far greater distances is true, but falls into the "watch me pull off this neat trick" catagory of things. Yep, I can hit a man-sized cardboard target at 100 yds, and one of my sons can shoot 4-6" gps at that range (he's a former Marine MP), but ask yourself if you could do it if the B-s-t-r-d was shooting back?
For the vast majority of us, using pistols or revolvers for what they were designed to do, kill men intent on doing us bodily harm, they are short range propositions. So in my opinion, the ghost ring - peep sight idea, tried and rejected in the past, adds unnecessary bulk to the piece, without a commensurate increase in accuracy and would be a PITA to pack in a holster. What we all need is practice with our chosen weapons, and a lot of it. Shooting them with "devices" in "action" games with some success in a very restricted venue, does not make them practical on the street or in the woods. If your interested in experimenting for the heck of it...have at it.
JMHO, Rodfac