As you might guess, the upgrades are a direct result of the Glock 19M and 17M development for the FBI pistol trials. Glock made even more tweaks to the pistol and rolled it out to the civilian market as the Gen 5 Glock.
In addition to the standard MOS plate system, Glock also removed the large window at the front of the slide on the Gen 5 guns. Sadly I don’t have a Gen 5 Glock 17 or a Gen 4 Glock 34 to compare slide weights. Even though it I wouldn’t call it the most reliable information, what I found on the web suggest that the slide mass has not changed from the Gen 4 G34.
The Gen 5 guns get a brand new coating called NDLc that should improve performance in adverse conditions as well as reduce the possibility of holster wear or scratches. Glock has also added the Marksman barrel to the Gen 5 guns that reportedly increases accuracy. The only way to really know is to get the gun out to the range.
The First 1,000 Rounds