Have you considered having elite vampires alert nearby minions somehow?
Maybe it would be interesting if an elite vampire going into combat would alert nearby minions to attack its target, and an elite vampire getting silently killed caused nearby minions to investigate the spot as if they heard a noise.
That could be a neat way to give elites an buff of sorts would vary based something that is visible to the player. Also the player would have a some different options to deal with it, like drawing the minions away from the elites, taking out the nearby minions first, locking the minions out of a house, or quickly leaving the spot where they quietly killed the elite before the minions come along to see what happened.
I guess this would also come with a bit of a lore bonus as it could imply, or be explained as, a sort of one-way "link" between the elites and their minions.
It could be something worth considering if you haven't rejected it already.