With Documents to Go, you can create and edit documents as local files and later choose "Save As" and save it to Google Docs, but it will not update or replace a previous version, instead it gives you two documents with the same file name but a different time stamp, which to me becomes a horror to manage. If you can trust Google's cloud, your better option is the Google Drive App for your tablet. Marking a file as available "Offline" will place an editable version on your tablet. Once you are reconnected to WiFi you can "synchronize" your edited "Offline" document with Google Drive and have the document updated in your Google Docs. I will create a step by step guide, if there is enough interest in Google Doc Sync.