Anyway, I'm sure you are correct and I've just over-thought the situation. But I wonder if an 8-year pistol (or better yet, an 8-year old magazine) offers the same amount of added pull weight?
I think that it is always wise to examine and question the functioning and reliability of one's different handguns. That is one reason that I visit this forum, for all of the great firsthand information!
With my eight year old G29, and mags of that vintage and newer, it is still a tad more difficult to get in the tenth round, it still requires more pressure to seat a fully loaded mag, and there is a small additional amount of effort required to rack the slide with a fully loaded mag. None of these seem excessive to me; but noticeable, yes. I agree with your observations. With my last post I was saying that in my eight years of carrying and shooting my G29, that I have not had any problems due to any of this.
The "limp wristing" problem can happen when I purposefully attempt to make it happen. (And not every time.) Very loose grip on the pistol. I watched someone new to handguns shooting his G29 for the first time have the same problems at the range. This was about 7 years ago. It was corrected for him by using a good "firm" grip. (He was flinching and barely holding onto the pistol.)
Let us know how your G29 proves out at the range, regarding the full mag/slide situation.