If I have to explain, you wouldn't understand.
For me there's no real difference between S and N serial numbered, three screw guns. I do, however, prefer guns that are old enough to have come with Diamond grips, which could be S or early N guns, but it's not a deal breaker.
Lol, I get it. They are a mechanical work of art. My only point was its a "big" gun for a .357.