Upon further playtesting this evening, I've reduced the number of Will-o'-the-Wisp and Hypnotic Specter from three to two, and replaced them with Vampire Nighthawk. This gave me a bit more flexibility when blocking creatures that were a threat to Chandra, the Firebrand and my life total. I've also found the Vampire Nighthawks can be useful when equipped with Fire Whip or Viridian Longbow as a one-shot kill due to deathtouch.
I've also reduced the number of Hymn to Tourach from four to two, and replaced them with Liliana's Caress. I've also reduced the number of Megrim to two from four, and replaced those with Liliana's Caress as well, as they're cheaper to play.
Overall I'm pleased with the deck and will be continuing modification.