Wow!
I just made some tests with an animated model (open mesh, no LOD´s) and the stencil shadows worked, as if the mesh was closed. I used the model both as an NPC and as a player!
This did not work with the previous version

BTW: I (and the manual) mentioned LOD´s just as a possible workaround for this, if the shadows do not display properly. But now (with A6.4) it seems that the restriction is no longer there, and the manual should mention this.
Indiglow, that´s a great discovery!