Hello, I really appreciate what you do guys. It is very good tool.
Generaly I like the way you implemented the tool and I would like to share my thoughts with you. If you will think about it good. If you dont have time or you see priorities elsewhere I understand.

Weighted normals
My colleague created script for weighting normlas similar way as maya do. This would be nice to have in your tool. Please visit link for more info. This feature is useful for example in game development where you can save some polycount with this. It is similar to your feature when you select face a adjust normals for it. This one is automatic for whole mesh.
link

"Copy face" operator for more faces
Select normal for editing by clicking
Relative rotation of normals ( without unifying )