LOL, I knew this was eventually going to happen after the debate in the Rise thread.
I say they don't need fangs to be 'functional', however, fangs have become part of our imagery when it comes to Vampires.
Just as we now tend to picture Werewolves to still have some human aspects when shapeshifted, however in the original tales they would completely change into a wolf. It all comes down to imagery.
After all, the original western 'vampires', Vlad the Impaler, Madame Bavory didn't have fangs. Wasn't till Stoker came around and added them to his little tale.
As to me, I prefer the allure of a Vamp without fangs. Simply because it makes them that much harder to differentiate from normal humans. After all, the thing that makes the serial killer so scary is he/she could be the guy/girl next door. Now think about one that's nearly immortal and out for your blood.
As to the burger meat...well technically it wouldn't need to go that far. After all the two major arteries, the juglar and the one in your thigh, are close enough to the skin, that one could easily pierce them with their teeth without damaging too much of the other tissue. But hey, you get a rambuncious vampire....