I could imagine that sneaking would still work, you could probably sneak up and bite them without them knowing.
Though if the Vampire Lord CAN sneak then they better add it to Werewolves soon. I want to be able to sneak up on my prey!
Werewolves do still gain the benefit of certain sneak perks. My Breton picked up the Light Step perk, so I wouldn't set off traps, & it even works in the Beast Form.
I can hop up, & down on pressure plates as a several hundred pound wolf creature, & they won't go off.