Only a couple of them are casters. Mostly the casters are named. All vamps cast invisibility, and can see through Invis, invis to undead, and sneak/hide. All vamps have a procurement that happens randomly that is a 200dd lifetap. All vamps randomly flurry and rampage. All vamps seem to be bugged where they will randomly warp back to their spawn when you get them really low on hp. Then they regen really fast and come after you when you get back into aggro range.
I've been quading the Coterie Legionaires for about 3 weeks now. They have really low hp, moderate resists, and drop decent plat and money loot. They also drop items for faction quests in Katta.
I figure, Vamps in Luclin are kinda like Sarnak in Kunark.