I've got the MMC box bar tritium set on my G19, and it's okay.
The allen wrench to adjust elevation and windage is too darned small, and it's easy to lose. I'm not very happy with the relative brightness of the front dot; it's weaker than the rear bars.
It's hard to use against a target with black background in normal light due to insufficient contrast. It does work fine in low light conditions. My brief test at the range confirmed this.
Until I lit off a 115 grain FMJ. Goodbye night vision.
If I install nightsights on my Sigs, I will seriously consider Meprolights. They have a white outline on the windows that work fine in the daytime.