FWIW, in an armorer class when the nylon disconnector was first introduced, we were told that it had withstood extended factory endurance testing just as well as the steel part. The factory instructor who explained it said that had meant shooting at least 25K rounds.
Interestingly enough, we were told the common way the nylon disconnectors were sometimes broken was during disassembly & reassembly
by inattentive armorers in the traditional double action models. Having to use a pin punch to push the disconnector tail around the drawbar's disconnector tab in the TDA guns required some care and attention to the amount of force used. It's understandable that someone not trained and experienced in installing and removing the disconnector might unintentionally damage one while removing or installing one, as well.
BTW, the disconnectors are installed differently in the TDA & DAO guns. In the TDA guns the drawbar is connected to the trigger first, and then the disconnector is installed, meaning the disconnector tail has to be carefully moved around the installed drawbar's tab during installation. In the DAO guns, the disconnector is installed
before the drawbar is connected to the trigger.
There were a couple other advantages to the nylon disconnector.
The tolerances were consistent, for one thing. The older occasional "long tail disconnector" problem, that required careful stoning of the disconnector's tail (bottom) to adjust the length of the part, was no longer needed. In later 3rd gen armorer manuals the problem and corrective action for the older steel part was dropped from the manual, since steel disconnectors had been replaced by nylon ones in current production LE guns.
The other advantage was that the tail's movement running up and down the drawbar's disconnector tab (ramp) was inherently smoother. Nylon has reduced friction against steel, and is 'self-lubricating', so to speak.
Toward the end of what became 3rd gen production, we were told that there had been some discussion at the factory regarding bringing the steel part back ... but not because it was any stronger or more durable in actual shooting. The reason being considered was that the steel part was less likely to be damaged by ham-handed or inattentive armorers.
Didn't happen, though, as the 3rd gen's were discontinued.
