After some further analysis the following bug report was sent to Apple via Feedback site.
iCloud's Documents & Data create a number of issues for network users.
Steps to reproduce:
1. Create a clean installation of OS X Server (10.8.1) with properly setup DNS, OD Master, Network users and AFP. Network users have their home folder on server (In my configuration that network home is placed on the second hard drive of a Mac mini, i. e. not on the startup drive).
2. Create a clean installation of OS X (10.8.1), bind it to the server.
3. On the client machine: log in to a new network user.
4. Sign in to iCloud using an AppleID, within the System Preferences (make sure Documents & Data are enabled — they should be by default).
5. Launch TextEdit.app
Expected functionality: TextEdit should display a window enabling the user to use iCloud, or open an existing file from the file system, or create a new one.
What happens: Nothing. Console reports:
TextEdit: RVS:__54-[NSRemoteSavePanel _runOrderingOperationWithContext:]_block_invoke_0315 : Timeout occured while waiting for the window
TextEdit is unable to save files. Invoking the save dialog doesn't do anything (Console reports the same error as above), closing the window either. TextEdit may have problems exitting properly and may need to be killed.
Pages shows crippled open file window, which doesn't allow the user to select files from iCloud.
Pixelmator is unable to save files — in a similar fashion to TextEdit.
Workaround: Disable Documents & Data in iCloud preference pane. All applications work as expected (but without the required functionality).