I have tritium Night Sights on the front of my 60 Pro and Governer, as well as front & rear on my new 2" 632 Pro. You can see that they are 'there' - in total darkness. In any kind of light, the big orange ramp on my PC627 UDR is far more visible. A HiViz fiber optic front sight is easier to 'pick up' in low ambient light conditions, too. In fact, the rear fixed tritium sights on my newest - the 632 Pro shoots 3-4" low at 7yd because of the short rear sight height - and they don't have a taller one.

Not a tritium 'Night Sight' fan here!

Stainz