Sadly, I still haven't learned to play the deck fast enough to be competitive, so ended up going 0-1-3 (yes, 3 draws!).
Round 1: Omnidoor Thragfire (4-color). Scary deck with a TON of ramp using the new Urban Evolution which acts like a mini Sphinx's Farseek. Ramps into big planeswalkers, multiple Thrags, Omniscience and other fun cards. I just couldn't deal with all the lifegain from 3 Thragtusk hitting the board. Lost 0-2.
Round 2: Bant Omnidoor. A less threatening version of the game 1 deck - mostly durdled around with Chromatic Lantern and Gilded Lotus. He was playing slow and not paying attention so we drew game 3 when I had control of the board. Highlights: Digging 6 cards deep using Jace, Architect of Thought and two Think Twice to find Pithing Needle the very turn after Door to Nothingness came into play; also, turn-4 Slaughter Games naming Sphinx's! Draw 1-1-1 but very much in control of game 3.
Round 3: Melissa DeToro's Bant Wolf Run deck. SUPER scary deck that uses a typical bant-midrange shell with Kessig Wolf Run to go over the top. I was able to control the board game 2 with an Olivia Voldaren to steal 2 Thragtusk. It eventually devolved into killing him with 2 Rakdos Keyrune which are Supreme Verdict-immune. Draw 1-1-1, didn't get to start game 3.
Round 4: Esper Control. A very standard Esper control deck. Game 1 I won due to Syncopating an all-in Sphinx's and then doing my own Rakdos's Return to tap out the very next turn (for X=6). Game 2 got Witchbane Orb'd and was sitting on like 4 dead cards by the end of the game. Went 1-1-1, as we didn't have time to finish game 3. Witchbane is brutal against bonfire, rakdos's return, Liliana of the Veil, and any sac-instants.
Overall: Pretty happy with the deck; had some awesome plays, even if no wins. Witchbane Orb is brutal and Sphinx's Revelation has warped the format (it was in EVERY deck we played against). Siding in skullcracks may be more useful that simply more counterspells, though a countered or Slaughtered Sphinx's usually meant a win. Card advantage is difficult for Grixis to generate, so I may go with more Jace AOTs. Thrags also suck to play against as its really difficult to interact with.
Takeaways: Sideboard Skullcracks. More Jace, Architect of Thought for card-draw and Liliana of the Veil to lock their hand down late-game or as a sorcery-speed sac. Pillar of Flame was surprising often a dead card - may go more with Searing Spear to go more into instant-speed and to deal more with the massive amount of Thragtusks. Need to learn how to play the deck faster as there are a LOT of control decks out there!