I just purchased and installed my second set of Heinie night sights on my G23. I have the straight eight, slant pros which utilize a single tritium dot on both the front and rear sight.

For those of you who want an alternative to a 3 dot sighting system, these are a great option.
During the day, there are no white dots or white rings distracting you from the top of your sight blade.

I would normally consider the sight picture on these more of a target style set of sights, however, sight alignment is very fast and easy. At night the tritium dots show up well and you just align one dot above another.