Today the wife and I put a little over 100 rounds through my Glock 19 Gen 4 FDE, bringing the total round count to around 400. I have been pretty pleased with the ejection while I have been shooting, but my wife has had some erratic ejection and brass to the face, most likely due to her grip.
Just to see if it would help at all, I installed a White Sound HRED before this range trip. It did not seem to make much difference, good or bad. Everything continued to work fine for me, and she got hit in the mouth with brass. In fairness to the Glock, my wife was getting some pretty weird ejection with her M&P 9c as well, which I why I still think it is grip related.
At the end of the session, I decided to take some quick cell phone videos of the ejection with the Glock 19, as well as a M&P 9c and M&P 9 Shield.
Anyway, here are the videos comparing the ejection, all shooting 147 grain Speer Lawman:
Wife with Glock 19
Wife with M&P 9c
Wife with M&P Shield
Me with Glock 19
Me with M&P 9c
I don't have much of a useful conclusion for you guys, other than that the HRED didn't do much in my case, and I am really impressed with the force the brass comes flying out of the Shield with!