There are a variety of sights that can be installed on a defensive handgun. For the most part, they will all work on the range; it's when you're panicked and fighting for your life that real difference can be found. In those instances, a phenomenon known as "target focus" occurs. This is where you're focused on the target, which can make it deadly difficult to shoot a handgun accurately if you can't see the sights.

XS Sights applies the "express sight" concept to their handgun sights, and it's a viable option. These sights are also a great choice for older shooters afflicted with presbyopia.

This video from the shooting range shows a visual comparison of various sights: