It doesn't change him one bit. That was Englehart's intention with him, to make him more human than synthezoid. It's only stories after that, that kept pushing him away from that concept, because writers chose to do the opposite. But he was supposed to be like Data. Regardless, he is still the father of the original Billy and Tommy. And he went through his own grieving process after he got back his memories and emotions. He's been through a lot and never should be erased for Mephisto of all characters.