Well Dawnguard has been out for a while now (lol) so has anyone figured out whether or not the Mage Armor perk applies to the Vampire Lord form?
That is... can Ebony Flesh/Dragonhide etc be casted prior to transformation and end up being carried over the the transformed state just as can be done for Werewolf transformations?
It working with Werewolf form isn't indicative of anything though. Werewolves also end up naked post-transformation, whereas Vampire Lords don't. There's no real reason that Mage Armor HAS to work with the VL transformation just because it's a transformation.