I've got several thoughts, but no real opinion on this since I've never tried the XS sights at the range .
I've looked at them in the gun store and thought I would not care for them .
One thing I notice MB and others stressing with pistol shooting is "FRONT SIGHT", not "sights".
I think this may be because , like with a ghost ring sight, the eye automatically centers the front sight.
Also there is the issue of trying to focus on the separate distances as the same time, rear sight, front sight, and target .
Another thought is that for self defense, which is usually at closer ranges does it really matter if you hit your attacker between the eyes or in the nuts ? How much precision do you need as long as your hits are on the target ?
That being said, as I stated before, the one time I looked a set over I really did not like them .