Far away, the optic itself becomes "visible" to both eyes, and, any shrouding of the glass starts to shrink down onto the reticle/dot making FOV smaller. Dots and reticles get smaller and somewhat dimmer the further out they are.For Rifles, they have holographic sights, the holographic site technology is not there yet to be miniaturized enough for a pistol.
My AR-15, the Holographic is mounted pretty much on the far end of the receiver, much better than at the back, its not an iron sight.
It's really a try and see thing, but I was just pointing out some basics of having something at some distance in line of sight. There's no escaping it. But again, does one way or the other work better for the shooter? TBD for each person.