"Data loss and corruption is a serious problem for Google Apps users. Browse through the Google Apps help forums and you'll find hundreds of posts from users who have lost their data and need help."
Of course, Spanning Sync has a new product designed to help you keep your data safe, so take this pitch with a grain of salt. But the myth of your data being safer in the cloud than in the device you're carrying is looking a bit shopworn. Those of us who want our calendar data always available ignore this news at our peril.