We're working on moving all of the following object types into a "system" layer:
1. Overlays
2. PDF Hyperlinks
3. Scale Dimensions
The reason to move these into a "System" layer is so that when you duplicate layers, it doesn't have to duplicate all this data per layer for it to be visible.

When sharing a Project with users outside your workspace, we have a few options:
1. Automatically share system layer unless "No Layers" is chosen
2. Automatically share system layer if any layer is chosen
3. Only share system layer if it is explicitly chosen from the layers list when sharing.

We welcome any input for how you would expect it to work.
Yes I've noticed when I receive a revision on a project and I create a new layer for it, the overlays don't carry over to the new layer and I have to redo them. This should take care of that nicely