I know @verhoek set up an automated system for producing nightly builds that were signed with a different key (on the build server). I completely dropped that one, but I am sure it can be picked up if there is a push for it.
This is what I consider the blocker for a non-beta release. The database rebuild is super slow, and sometimes fails. For a production-ready system this should not happen.
There are also cases where the database suddenly breaks, but maybe that part is actually fixed now.
The shutdown is nice, but Duplicati should be able to handle a hard power off, so that is not a blocker for me. Symlinks and paths are working AFAIK, and some translations are complete.
Subfolders is a new feature, so I would not delay a non-beta for that.