In the 3D apps, It would simplify things if the MH meshes (and armors using it, because we have cut the MH mesh to be modular) used the mannequin skeleton, since there wouldn’t be additional bones to get in the way, and would likely reduce import/export times (I tried to import a metahuman head with all the bones and it took a long, long time), and we plan to have multiple clothing options for the different body parts.
In-engine, I may be wrong, but I can’t imagine having those extra bones being a good thing for performance? even if not weighted to any vertex, there would still be some overhead for them just being there, and we plan have multiple characters in a scene. And I believe it would be even worse given the fact that we need to have multiple SK meshes using that skeleton, to provide modularity.