In regard to the internal lock. All mechanical devices have elements in their design that are prone to malfunction. The more parts that can malfunction, the more malfunctions will happen. To illustrate (although a revolver thread), among the parts of a 1911 that are most prone to malfunction are, the extractor (looses proper tension), the ejector (leg breaks off), and the safety plunger tube (becomes loose). If those parts could be somehow improved or eliminated, there would be fewer malfunctions with that gun. Note the Ruger SC1911 with integral plunger tube. It eliminates a frequent source of malfunction making that 1911 a mathematical certainty to have fewer malfunctions than models with standard parts if ignoring for the sake of argument, all other extraneous factors. It is a forward-step in engineering design.
The revolver has few parts or fewer that the 1911 that are prone to malfunction. The extractor rod is known to become loose, but with the invention of Blue Locktite, that is no longer of concern. In short, the fewer parts, the better.
Enter the internal lock. An unnecessary part that has been known to malfunction. What it does, is provide a mathematical certainty that the chances for malfunction is more likely, however slight. It is a backward-step in engineering design, no more, no less.