I don't often disagree with Rob, but on this topic, I do. I've been carrying tritium sights on my service pistols since they first became available. Working a one man patrol car, at night, in Oregon weather, big city or country roads, or S. California alleys, in virtually every scenario you can think of, I have never had a problem aligning my sights to my intended target. I can not think of a single situation where I was in total darkness. Unless in a closet or photography dark room, there is always some ambient light. With proper technique, it is not difficult to distinguish front from rear night sights.
In some of the darker situations is where smart flashlight use is applied. FO sights are great when there is light, but not so much when the lights go dim.
My experience and opinion, your mileage may vary.