A single card is almost always more stable than an SLI. Stable as in general, it might make your computer crash more and cause problems with programs. But, the more viable consequences will be having to wait for games to fix SLI problems, having to deal with more heat being produced, and having to provide more power to the cards. A single, faster card is the way to go for a new build, since you'll have more room for GPU upgrade in the future, like adding another 760.
But sure, not everyone with SLI has problems, and having SLI doesn't automatically mean you'll have less problems than with a single card.
