I seldom update the blogs with the latest WP update. Same with plugins. If I'm putting up a new blog I'll get the latest and greatest but after it's up and everything is working I don't like to mess with it. Sometimes the updates break things that are working.
If I have the time and a reason for doing it I will upgrade but for the most part I just leave things alone. If it's working well why mess with it?
MS is great for checking rankings but it's even better for finding good keywords and letting you know what links the competition has. I like it much more than using google tools.
It's also good at finding content you can use to write new articles. Not so great at finding things to sell, at least for me.