Volkihar vampirism is no different than the base vampirism contained within the main game, with the exception of the vampire lord transformation, which is quite a downer. I would love to see a mod that changes that to make a volkihar vampire unique, compared to the thin-bloods of the main game. I would particularly like something like this to be done:

• Volkihar vampirism is its own unique disease, which doesn't interfere with the regular vampirism disease and would then allow maximum compatibility with other vampirism mods for the basic vampirism of the main game

Volkihar vampirism should be set up something like this:

Stage 1:

• 100% resist disease and poison
  
• 25% weakness to fire
  
• Vampire's Sight
  
• Vampire Lord Transformation

Stage 2:

• 100% resist disease and poison
  
• 50% weakness to fire
  
• Sun Damage (1hp/s)
  
• Vampire's Sight
  
• Vampire Lord Transformation

Stage 3:

• 100% resist disease and poison
  
• 75% weakness to fire
  
• Sun Damage (4hp/s)
  
• Vampire's Sight
  
• Vampire Lord Transformation

Stage 4:

• 100% resist disease and poison
  
• 100% weakness to fire
  
• Sun Damage (8hp/s)
  
• Constant -50 to Health/Magicka/Stamina
  
• No Health/Magicka/Stamina Regeneration while in sunlight
  
• Vampire's Sight
  
• Forced Vampire Lord Transformation (As soon as you reach stage 4, your body will no longer be able to retain the human form and will be forced to transform into and remain as a vampire lord until you next feed. You will be forced to trasform back into your human form after 30 seconds have past since you last fed. This should allow the player ample time to clear the room before they're forced to transform back.)

The pupose behind these changes would be to emphasize the vampire lord form as being the focal point behind this form of vampirism and to encourage it's usage. Despite bethesda's efforts, a level 50 player will still feel more vunerable as a vampire lord than in their regular human form. This mod would nerf the player's human form a bit and encourage the usage of the vampire lord form. The reasoning behind removing most of the abilities that vampirsm provides the player while in human form is to also emphasize the vampire lord form. The removal of regen stagnation and it's replacement with sun damage serves to differentiate this form of vampirism from the base form in the main game. Volkihar vampirism would be made out to be much more high risk/reward than the base game's vampires.

This is all for when Dawnguard has been released on pc, of course.