Document Sets are a nice thing, because you can use them to group documents, set unique permissions on them (which are inherited by child items), easily manage files in file explorer (with Document Sets as folders) and add additional information (like in normal SharePoint items).
We would like to leverage these features to store information about projects & experiments incl. documents in a central DocLib. Experiments are always belonging to specific project. Data security is really important - users from specific groups should only see data for their projects (based on permission on parent Document Set = project).
Using nested Document Sets (project > experiments) comes really close to what we need. But unfortunately, it seems that nesting is not really supported, at least in UI of SharePoint 2013. You cannot select Document Set content types as allowed content types within another Document Set (in site content types). And in DocLib you can only insert this type of content type via UI when you are on top level.
Actually, it is possible to create experiments on top level via UI and then move them into a project Document Set using file explorer (WebDAV) - it seems to work nicely (incl. security). But I cannot tell my customers to create experiments in this way.
Is there any way that we can achieve our goals using nested Document Sets (without having to move Document Sets in file explorer)?
Is there any better approach for this scenario?