Sighting in the picture.
I'm just a newbie with very little handgun experience, but I'm a former geometry teacher.
I think we can all see that #1 and #2 are using the same sight references (the tops of the front and rear sights) so the line of sight raises from #1 to #2. For the shot in #1 and the shot in #2 to hit in the same place, one of the sights is going to have to be adjusted, right?
I'm told people use "Pumpkin on a post" (#1) for competetion, so they get their pistols sighted in to work that way (at a limited range, I might add.) Also the size of the "pumpkin" will have a lot to do with where the bullet hits it, correct?
#2 & #3 are using different reference points, and the respective lines of sight are parallel 1/16" apart. Can you adjust your sight for that difference in elevation even at 7 feet? You just compensate based on your experience and practice, right again?
My point? A choice between 2 & 3 should be a matter of personal preference, while choosing #1 would be more practical if you always use a specific target at a specific range.
Now, before any of you decide to flame me if you disagree, think about the ballistics and geometry. I'm not saying one sight picture is right and the other wrong, but this is how it works. If a ballistics "expert" out there understands this different than I seemed to describe it, let me know.
But it would seem to me that you'd have to adjust your sights for either #1 or (#2 & 3) and you couldn't have it both ways.....
(If I've erred in this, it's more likely to be my explanation than my understanding, but hey, there may be some stinkin' thinkin' involved as well!)
There's a fundamental flaw in a system that passes laws that put an onerous burden on law-abiding citizens, but fails to prosecute the criminals who break those laws.