techdevout: The GOG release of Risen does seem to be compatible with the unofficial patch v1.3.
The store page lists that the game is patched to v1.11 - I suspect this is a typo, since a quick search reveals that the latest official patch is v1.10, which is what the unofficial patch requires.
Since I've only started the game, the only way I could test the unofficial patch was through the quicksave functionality (i.e. with the unofficial patch, quickloading should load the most recent quicksave, not simply the most recent save, as is the case in the unmodded game), and it worked as intended.
Barring any other issues, it should be safe to use the unofficial patch, but should anything go wrong, uninstalling the patch is a simple matter of manually removing every file it installs, since it does not overwrite any of the original game files.
I personally bothered our techs to ensure that we had patch 1.11 installed since it's not easy to see it via the main menu :)
So, in short, yes the game is patched to 1.11 the last official patch that removed the DRM and included the changes from 1.10 :)