Haha, well I won't flame you, but most folks have a helluva time sorting out S&W pistol models already... your theory actually confuses that even more. Even so, I see your angle.

Each Generation was intended to be an improvement. The 2nd Gens offered a new (optional) adjustable rear sight, ambi decock lever and the added firing pin lock. On the full size 9mm's, a new steel frame was an option.

The 3rd Gens added new models and new firing systems as well, but the upgraded features were new and improved sight options (front and rear) but the big upgrade in my opinion was the ergonomic improvements... slimming the pistols down, shaving metal in important places for a better grasp and whack down many of the sharp corners and edges.

My 469 in particular has some extremely sharp points and edges, they are begging to be lightly taken down.