Here's one of the big problems with airing your "pilot" episode as part of the run of the series from which it spins off: if you decide to make any cast changes, those changes will be pretty obvious.

Case in point: The millions of people who watched the Private Practice spin-off episode of Grey's Anatomy saw Merrin Dungey playing Dr. Naomi Bennett, the friend and fertility expert that Addison Montgomery visited in L.A. because she was looking to have a baby. However, come fall, Dr. Bennett will be played by noted Broadway actress Audra McDonald (pictured), according to the Show Tracker blog on the LA Times' web site. There was no word on why the role was recast.