Interesting, I have noticed ("excuse based") defensive mechanism when it comes to this topic ... most people I have witnessed start to use very poor arguments of why they want to stay on social networks ... very similar to people with "un-noticed" alcohol problem. But yes, nothing magical happend without it. Just maybe realization how stupid it is.
This about sums up my experience in deleting Facebook. It seemed like a shallow form of communication at the time, now as an outsider it feels even more so. I do feel less stressed and emotionally burdened by constantly being exposed to everyone else though.