When baking normal maps from a high poly mesh to a low poly mesh using cycles, if the low poly mesh has customized vertex normals, cycles will not use them.
I uploaded a test file here which contains a simple highpoly (using a material with the new blend node) and lowpoly with custom normals (created using the Y.A.V.N.E. plugin):
Using cycles for baking I consistently get incorrect normals baked down.
Custom normals are very often used in game development to get higher quality bakes and more flexible normal maps. Getting this feature to work correctly in Blender, used together with the new bevel node will make Blender a very powerful tool for producing PBR ready game art.
If anyone has time to take a look at this, I'd be very grateful! Hit me up if you need more test cases to work with and I'll gladly set them up.