Round or diamond shaped peep sights

[Mtbkski]

Looking for a rear Peep Sight to replace the junk one that fell apart on the AR I have. Came across this and was wondering if anyone had used the diamond shape peep and what they thought of it. It seems like it would make centering the post up front a bit easier in the rear sight.

[Hawk]

Your eye will naturally want to center the front post in the rear peep regardless of it's shape. It's built into your brain to want everything to be symmetrical.
I used to confirm the centering every time I built my position. 5 years and 10,000 well aimed rounds later, I don't check anymore because I'm confident nature will take care of it.