So, I'm doing a SCS + SR run of the game, and the second major quest I'm running is Windspear Hills. 'Smarter' vampires are in a whole different league than anything else in that dungeon, including lycanthropes and golems which, by the way, give more XP.
It seemed like a little tough nut to crack, so I decided to apply a few buffs to my Cavalier. This includes: Chaotic Commands, Improved Haste + oil of speed, Improved Invisibility, Negative Plane Protection, Divine Might on top of potions of strength, constitution and dexterity, potions of invulnerability and defense, and the Amulet of Shield. I threw in Protection from Evil for good measure. I also had some fine wine to go along with all that cheese, mind. The thing is, that's the least-resistance path. If I want to involve the rest of the party, I need to spend even more resources to spread around Chaotic Commands, level drain immunity, etc.
I'm a huge fan of this mod. I'm not a very good player, but I've played through these games several times with SCS. I'm all for challenging encounters, but this is just silly. I don't think it's reasonable to need every buff in the setting and then some from Eberron to pull through, especially for a mandatory encounter, in an early game dungeon. This is a trash pull, not a boss fight.
TL;DR: these vampires are hella overtuned. Smarter vampires are cool. 4-APR, on-hit CON and level-draining, instant Feeblemind and Charm-spamming, fighter/thief vampires (plus a small army of adds), not so much.