If persay they didn't do any companions quests and got bitten by a vampire, becoming one is also true I'm assuming.
Khajiit have one of the most useful racial talents as the only race who can see in the dark without the use of a torch or a light spell/staff.
In how many ways can you benefit from being a Khajiit and taking up a werewolf or vampire affliction?
I know Khajiit in particular have the "Cat Claw" ability, allowing them more melee damage with their fists. Does this stack with being a werewolf and mauling enemies with your bare hands?
(I have downloaded Dawnguard, but I haven't started the quest on it. So far all I've spotted were vampires, hell hounds, and gargoyles. I know there are vampire and werewolf perks, but I know nothing about them yet. Feel free to share them if you want.)