Personally, I think there should be a legacy unlock to switch animations for mirror classes. Example: Jedi Consular's Project becomes the Sith Inquisitor's Shock or vice versa. However, since we are on the topic of defections. I love playing the Jedi Consular, but I'm also the darkest Jedi to have ever lived! So faction defection would be awesome for my Consular.
Also while talking about defections, I think Bioware should make "Fallen Jedi", "Dark Jedi", "Enlightened Sith" and "Redeemed Sith" into titles. "Fallen Jedi" for Jedi who have reached Dark IV and "Enlightened Sith" for Sith who have reached Light IV. "Dark Jedi" and "Redeemed Sith" could be given once given Jedi or Sith reaches Dark II and Light II respectively.