Yeah, I have to agree with the opposition. Vampires need to cause chaos if people are ever going to hunt him down. Otherwise, people will treat them like pasturing their cats outside during a siege.
That said, I kind of agree, but on a different principle.
Picture it this way, you want a hamburger, your neighbor has a large herd of cows, so you dress up as a cow and go into his pasture. If you slaughter one of his prize cows with the golden cowbell and a red ribbon tied around its horn, he's going to notice. If you slaughter one of his average same ol' same ol' cows, he won't notice as quickly. Likewise, vampires should have a certain level of self-preservation.
When a vampire gets hungry, he should check everyone whose sleeping in an owned room. He then targets the person with the least amount of friends. If everyone has more then five friends he'll randomly pick one whose sleeping regardless of the number of friends. If there are no owned rooms, he will check the hospital, and if there is no one in the hospital, he will check the dorms.
This is because the person with the least amount of friends would be less noticed when he goes missing, by both the player and the other dwarves. Having a vampire kill your broker causes a certain amount of Fun. But you'll notice it very quickly.
I suppose it comes down to what you find more Fun. Having a vampire kill your broker, or having a vampire kill six skilled (not legendary) workers.