OK, UtF over Disfigure. Replace it if you can, unless your meta all runs very fast aggro, like boros.
So 4 Tendrils, 4 UtF, and 4 Gatekeepers is a good level of removal for your meta, good. That seems right.
As for not running Hexmage, my bro's explanation was that she was simply ok. He said that the main hard-hitters of vamps are: Bloodghasts, Vampire Nighthawk, and Nocturnus. Malakir can be a finisher in a white-heavy meta as well. Hexmage is ok, but not as good as duress for many reasons, among them the fact that she is one of the worse vamps, albeit a good SB card vs. planeswalker-heavy decks.
I would simply say:
+2 Marsh Flats (You know that
)
+4 Duress
+4 Urge to Feed
+2 Kalastria Highborn
-2 Swamp
-3 Hexmage
-4 Disfigure
-3 Malakir Bloodwitch (Unless it's a white heavy meta)
Most of the these are simply moving from SB to MD, with the exception of the Marsh flat/ Swamp and Urge/Disfigure.