RE: Some Streamlined related....
Two-pin cup may become wobbly, but they won't break. Plus, wear will clearly suggest it's time to buy a new one.
Euro pin systems are simply ill engineered. The screw part in one piece pins are the weakest because of the edgy machining of the screw, but anyhow machined metal will eventually develop tiny breaks that start major ones under fatigue.
In other words, an Euro pin may break, two pin cups just can not (unless extreme cases that I can't imagine but are still possible).
Of course, the occasional swim in is not an excessive trouble; and even less of a problem is for me.