Custom Split Normals Data broken by Subsurf? I am using the Data transfer modifier to transfer normals from one object to another. This works fine when it is in the modifier stack after the subsurf modifier. If the subsurf comes after, the mesh reverts to it's regular normals.

This is not a problem if leaving the modifiers, but I want to avoid this because Data Transfer of normals adds a big delay to the start of renders. I can create a Custom Split Normals Data layer and then apply the Data transfer. However, this is then the same as having the custom normals before the subsurf, so using subsurf again reverts to the regular mesh normals.

Is there a way to stop this, or a work around? Could I bake a normal map of the data transferred model to the default model and get the custom normals as a texture instead (perhaps a different question: Does baking a normal map include custom split normals layers.)
I was able to get around this by baking a normal map from a version of the model with the data transfer modifier on to a regular version of the model without it. Both had subsurf. I then used this normal map in the object's material.

I baked the normal map in Blender Internal as Cycles was giving me artifacts and horribly pixelated results, but I do not know if that matters. I may just have been using the Cycles baker incorrectly. I am using it in Cycles without issue (tangent space for the bake.)

I am still looking for any other solution, as use of a normal map isn't always possible, such as when using normal editing Addons.