Depends on what you're shooting at. For target shooting at paper black on black is still pretty hard to beat. If you are shooting USPSA you will seldom see black on black, almost every one uses fiber optic sights so you can find them faster on moving targets, etc. For hunting black sights can be a problem when you are shooting early or late & the target is standing in the shade or brush. Pretty hard to get a good sight picture against a dark hide in a dark background with black sights, many of us want some contrast, especially when some get a little older.
The rear peeps can help quite a bit for focus with older eyes, I sell quite a few of them & also sell fiber optic fronts for the pinned Rugers & S&W guns. Still, black on black has it's place many times if the front sight matches up size wise to the rear sight. Most all of my front sights are narrowed to 1/10" from the original .125" factory, it helps!
Here's a Rock Chuck I shot yesterday with my 8 shot 327 Blackhawk. The front sight has been narrowed to 1/10" & then painted white & then bright orange. I had to get on him really fast, he ran out of the sagebrush & up the Lava rocks & stopped right at his den hole. When they do this you've got about 3 seconds to make a shot. I was on my 4 wheeler & shut it off real quick, grabbed the 327 & punched him with a 135 gr. Ferminator HP through the head at 32 yds. I found that orange sight really quick, black on black, maybe? The holster is my great Barranti cross draw & one of his 10 round cartridge holders.
Dick