Part of the benefits of being a member of the GSSF and attending matches is the factory armorers are there. They will check out your Glocks and replace any parts that are worn. Now, even though I'm a trained and certified Armorer, I like to have my guns looked over at least once a year by the pros. An upside is that the factory guys are not very reluctant to change parts, so your Glocks always stay factory fresh.
So, after checking out all three Glocks, the only thing they did was replace the trigger bar on my G17. I had noticed some scratches on the top of the cross piece, and I guess he thought it was enough to warrant replacement. Better safe than sorry, I suppose.
Then, when time came to put the slide back together, I noticed he also replaced the rear cover plate. I think it was because he had misplaced the original. I was sad. This was an original piece from 1992. Now I am left with the frame, the slide, and the barrel.
Now, as a downside, this meant that part of my cleaning routine on Sunday was a 5 cent trigger job, just an abbreviated version of the 25 cent trigger job. All I had to do was polish the new trigger bar.
I dry fired a bunch since then and I can't tell much difference. That's an upside.