ignored in the alembic file.
that exported alembic file may not contain normals. Currently alembic exporter on blender exports perfectly smooth meshes without normals. In addition, VL.Alembic does not perform vertex smoothing at runtime, so any mesh that does not contain normals is imported as a flat meshes.The fastest solution to this, as far as I know, is use the NormalEdit modifier before export to make blender recognize custom normals and set the Mix Factor to 0.
I think your way with the bone is much more performance friendly.
I think this is true in many situations. (I think alembic was originally designed to handle animations that are difficult to handle with bones, such as simulation baking.) However, to do this on the GPU, I have added a sample from VL.Alembic 0.3.0 that bakes vertex animations into textures and plays them back.