One thing to ponder is that once Dan went to having an actor who was in that episode do the voice over, that it may be a small spoiler in a way. Before they released the episode guide, I used to count the actors who would be in the show, knowing it was usually 4-5. (Its a rare episode with 6 until 1897 when budgets apparently got bigger, but still very rare to have more than 6 speaking parts except on pivotal episodes.) Sometimes, from the voice over I could tell someone who would show up later, sometimes the appearence might otherwise be a surprise.
By the way, the current episode guide has a few errors on the voice overs. I think Grayson was the second person other than Alexandra to do one. I marked it in my copy a while back. Nancy B and KLS did some early voice overs as well. While it could be noted Jonathan did very few opening voice overs, again notice they were not often done by the person in the first scene, such as Jonathan usually was.
Michael
Your Cousin from Virginia