I've seen fiber sights in action and they aren't all that hot. Lets say that you're either a cop or armed security type the only time the fiber sights would work is in a well lit area. They work by absorbing light. The tritium (Mepro, Trijicon, etc) produce their own light and really do work in the dark, you could be in the middle of a forest with no moonlight and still see your sights.