I have never had a set of sights returned by a customer for breaking or coming apart. I did have one set on a customer's gun that went dead shortly after being installed, one side of the rear sight died. It was replaced by Tru Glo without any issues. I've had that kind of failure with other brands, including the factory sight on my Tomcat. I don't have any problems with my Glocks and TFOs. I clean and lube with Gunslick bore foam, Hoppe's #9, X1-R, and Gunscrubber. Maybe my experience is limited, but I've had no problems. I'm going to buy another Glock soon, probably a 17L or a 34, and I'll add TFOs to it without concern.
The TFOs are the only sights that offer something more than plain night sights. Every other manufacturer (and the rumor is they're all made the same and sold under different brands) just makes a dot that glows at night. In the daytime they're no different than painted white dots. The TFOs combine the best of day glowing fiber optics and night glowing Tritium sights.