There may be something in this chain problem. I, and a few other locals, are trialling a prototype Durace chain - apparently it has a different finishing method. I have not cleaned it as often as I would normally clean a chain, and have ridden it in all sorts of crappy weather and road conditions, and so far it has not missed a beat. I understand when I have completed the trial it will go back to Shimano for some kind of analysis.
While I have not (touch wood - not that kind of wood you dirty buggers) snapped a chain, and have mainly used Durace or top shelf SRAM chains, I do feel a whole lot safer on the 1/8 chain on my track bike. It looks like it is built for strength, and I would always prefer strength over a modest weight saving.