would vampire's hit points go down?

[Ruvion]

I think it's fair to have variant vampires with lower Strength and Dexterity boost, say +4 to Strength and +2 to Dexterity as opposed to a +6 and +4 respectively and give extra hit points based on Charisma bonus (since Constitution is not available).

 

[Mustrum_Ridcully]

I think it's fair to have variant vampires with lower Strength and Dexterity boost, say +4 to Strength and +2 to Dexterity as opposed to a +6 and +4 respectively and give extra hit points based on Charisma bonus (since Constitution is not available).

You could certainly do this, but the reason why every undead gains a d12 as Hit Die is because of the lack of a (Con) Bonus to his hitpoints, I think.

Mustrum Ridcully