Well, curiosity got the best of me, so I contacted Hopkins about the metal used in the connections of the Hopkins Endurance #48470 connector I was describing in the post above.
Turns out, they are NICKEL PLATED BRASS. The back end wire connections terminals as well as the inside the plug terminals on the front (blades and center pin of the 7 way, and all holes and ground pin of the integrated 4 and 5 ways) are all nickel plated brass. This is a very good thing. In fact, it is better than brass alone, and is more costly to produce.
As an example, I was recently shopping for triplex pressure pumps, and the nickel plated brass ones added a couple hundred dollars to the cost of an otherwise identical pump.
Another feature that Hopkins made me aware of is that this is the only connector that has a 3 year warranty. I'm not big on warranties, but if you are, then there it is. Finally, the Hopkins guy was talking about how they were trying to break the door off of one of these connectors in the shop... just to see what it would take to do it. They couldn't manage to, he said, and they were "beatin on it".
I bought this connector when the spring in my current Pollack brand connector would not fully close the door. This would leave the inside of the connector exposed and vulnerable to tire flung water and road spray, as well as dirt from the vacuum created in the back of the vehicle when the vehicle is moving forward at highway speeds. I didn't like that, and wanted a door on the trailer connector to shut securely. This Hopkins connector did, and has a neoprene seal built into the door to boot.
However, when I started to remove my Pollack connector, I saw a way to fix my existing door, so I chose to do that instead. Now that I've seen this thread, and responded to this post, and learned more about the connector I already bought and planned to return... I think I'll keep it. It's a good unit, even if goofy looking. It meets the need for a robust no fuss trailer wiring connection, and eliminates the use of translators and adaptors for the 4 and 5 way connectors.
It comes with it's own metal mounting bracket and rear wire harness sealing boot as well.
Now THAT's over analysis for you. Any day, any time, any place, any subject... even one as small as a simple wiring harness connector that comes free on most vehicles... I'll outgun ya!
