There are a few issues with custom normals workflow at the moment. For example it needs auto-smooth at the moment depending on the artist pipeline.
It would be nice to bring ability to preserve boundary vertex normals to a split tool (Y key).
For example, it is impossible to reconstruct such a model as 4 instances, saving UV space, because after split verices normals are changed, and they conflicts with normal map, giving a dent.
Thank you for custom normals preservation ability!
Indeed, it works with using rip, delete, dissolve, and knife tools.
But is it possible to support Mesh - Split - Selection (Y key) as well?