(I’m basing my quick mathssssss on wiki, don’t scream if it is incorrect)
Shotgun does 48 dmg with one pellet on 20 armor, which is vampire lurker.
48 * 4 = 192 One PB damage.
192 * 2 = 384 Two PB damage
390 - 384 = 6
Vampire survives 2 PBs, barerly, but he does.
192 * 3 = 576
Warrior survives 2 PBs, but not 3.
500 - 384 = 116 HP left. 110 HP adventage for warrior when it comes to PBs, he can survive some cheap damage afterwards.
Flurry is just a warrior’s punch, but better.
Tail Jab is just a warrior’s fling, but better.
Rush is not that easly comparable to lunge, one of the three adventages warrior has.
But rush is a Get Out Of Jail free card, because lunge can’t be used to escape, so it is kind of a sidegrade.
Ironically this means that warrior is better against lone marines than vampire is because of lunge and healing each slash 20 HP, but vampire is better against groups as he can escape easly.
Vampire lurker is a faster warrior, only slightly less tanky. He can be just as easly crumpled by a single marine with shotgun as warrior can, but warrior is slower.
Vampire could be just a warrior strain. Unironically.