I have carried and shot my G29 for coming on eight years. (And this has been my favorite CCW during that time.)
I always have a full mag, even with +1. Never had a bit of problems with any of the mags or the pistol because of it. I also use G20 mags with the G29. All of mine have been trouble free.
I do admit that filling up the 10 round mags is a chore when they are brand spanking new. I always start out with nine until they are "broken in" and then get in that last round.
I did "test" a few of the mags, leaving them full for a couple of years without using them. All went as advertised when finally used up at the range, and still work flawlessly.
Just my experiences.
Only real problem that I have ever had happen to me, and seen someone else duplicate with a different G29, is I can definitely have problems if "limp wristing". Good grip on pistol, no problems.
The lowest paid college major/degree in this country after graduation...
Now, go figure...