I havent been able to get anything close to usable with this method.
Ive set it up as follows:
The low-poly mesh is in both the High definition meshes list and Low definition meshes list. In the Low definition list, the path to the normal map is placed in the Highpoly normals override file section and the Highpoly normals override tangent space box is ticked.
The results of this method are on the left whereas the results of projection using the high-poly mesh are on the right.
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Keep in mind that I set the render quality high (Rays at 512) just to make sure it wasnt the quality that was causing the bad results.
I know that its preferred to use a high-poly projection as the results will always be more accurate. Still it would be nice to have this option too.