Not sure if this has changed since then, but around a year ago, I was using Google Docs to collaborate with a few other people on a school project. I lost connection to the internet, and when I reconnected, Docs popped up with an error message telling me that something went wrong and I had to refresh. That was the only option, though: it disabled all controls and I couldn't copy off the work I'd done that didn't get saved.

So, speaking for myself, I wouldn't trust these online office suites with my data or time. They also tend to lag more on lower-end hardware (I frequently use a netbook for notes, etc).