I've got XS Big Dots on all my carry guns and hit with them what needs hitting especially for those defensive situations. And we've all seen the YouTube videos of Yeager making long range shots with his G19 w/ Big Dots.
During a training class, the instructor was not a proponent of the XS sights and had some Sevigny's on his Glock. I was "called out" to make the head shot at 20+ yds. on a target after he'd done it with his Glock. All of mine hit their mark as well and the point of his demonstration was lost after that. It's just a matter of knowing your point of impact.