If you open a file into Quickoffice from mobilEcho, you can edit it as usual and you'll see the Save Back option, but when you go to save back to mE, Quickoffice will show a processing dialog and then close, mobilEcho will not launch as expected, and the file will not end up back in mobilEcho even if you start the app manually.
This issue is not specific to mobilEcho and will need to be addressed by Quickoffice.