That's what seems to me too, Component::_matrix was never used. What I'm wondering now is what effect will saving and restoring the mesh matrix will have. Did you try to save and restore while an actor was running a keyframe animation? It seems like it was always (0,0,0), because i remember it working right.
Besides, why does it only save the translation but not the rotation? This whole matrix stuff is fishy, and i unfortunately don't remember very well how it came up to be.