You may or may not be aware that there are actually two different versions of spring cups available for the firing pin installed in your Glock. One is the type commonly installed on Glocks in the factory and the other is called the “Maritime Spring Cup”. (Part# G3073)
A common misconception is that these cups are designed for allowing the Glock to shoot underwater. Contrary to what you have probably already seen on youtube, this is extremely dangerous, and even if you don’t sustain an injury, you have probably caused damage to your weapon. Glock does not recommend firing the Glock, or any pistol underwater without proper training.
The actual intent of these cups are to allow, during normal use, water to drain out of the firing pin channel a little faster when exiting the water and operating on dry land, as well as allowing proper firing pin travel if there does happen to be a little water still left in this area after the pistol has been drained. Glock does this by creating a cup with some of the plastic removed a little bit, reducing the sealing effect the standard cups may have when water is covering them.
The pros of these optional parts are that if you see yourself having to operate in a maritime environment, these may actually improve the reliability of your weapon by allowing for more reliable primer strikes and therefore ignition of rounds. As for the cons, there is not too much documentation on the longitivity of these cups companied to the standard ones, but it can be assumed that since there is 50% less plastic on the cup contacting inside of the firing pin channel, there would be double the amount of wear on the cups than the standard cups. I do know that there is a lot of documentation of Glocks running thousands upon thousands of rounds in endurance tests, and yes, they are running the standard cups.
As for me, I tend to run the standard spring cups in my personal carry Glock. I presently see no need for these cups for anything other than use in extreme conditions, and we all know that the standards cups fire just fine in the pouring rain (been there and done that). Unless the gun is actually going to be submerged, and then exit the water and going to be used without being drained, I see no real reason to sacrifice the proven durability of the standard cups and the longevity they provide the system they are installed in.