I think the mark of a safe airline is not so much whether maintenance issues and other IRROPS happen (they always will), but rather, how the crew and corporate handle them when they do occur. And it sounds like both of these incidents were more in the "technical nuisance" category than raising any sort of question of a profound compromise of safety and security of passengers & crew. And each time it happened, the plane was taken to maintenance for several days despite the heavy commercial incentive against doing so. There are other airlines that choose the latter, sometimes with dire consequences.

Personally, I lend very little thought to superstition when it comes to choosing the flights I fly on.