Just a quick update.
I got the firearm back from S&W today. The repair sheet reads as follows:
Replace Extractor
Replace Extractor Spring
Barrel Modification
Range Tested/Meets Spec
The "Barrel Modification" threw me for a loop. In examining it side by side with my other M&P 9c I can't see anywhere that a modification was made, but idk for sure (I can always call I suppose). I also notice that while they didn't replace the ejector it now has an angled cut whereas before it was flat. I appreciate them doing that.
Anyway, I took it to the range and ran 100 rds of 115 gr Blazer Brass through it. Not the best ammo, but I wanted to see if it would work with underpowered ammo. The first round went boink off the top of my hat and my heart sank a little. However, out of the 100 rds fired I would say 1-2 boinked my head total. The rest ejected to the 4-5 o'clock position. To be fair I may have limp wristed those rounds as I am a bit sick this week.
The rest of the function was fine. I wanted to give S&W the kudos for apparently fixing the issue.