The only chain related problem I've ever had was the outer plate on a spring clip split in half vertically.Personally, I've never had a chain fail on me. Know of several others though, especially one cheapskate that pieced a chain together from several left-overs. Found 3 spring clips in that one, nearly whipped him with it, I was that mad. He cost us half a day on a fairly tightly-scheduled trip.
One other memorable failure was after taking first place at Hockenheim with the H-D Sprortster in 1995. Unloaded the van Monday morning, started the bike to ride it up the ramp into the workshop, bloody chain snapped half-way up! Michael had won by about 30 seconds to second place, he could have coasted the last 500 metres! But we stopped using spring clips from there, I had about 5 chains of different lengths and a bag of rivet links for gearing changes.
IWIS chains used the outer plate to secure the clip itself. After assembly, with the outer pressed on, the plate was forced in the other direction to secure the clip, this worked extremely well. I also use this method on any other chains with tight-fitting outer plates.
piet
I rode gingerly the 15 km home from work.
Paul