Wanted to point out that Pillar of Fire doesn't work against Gravecrawler if your opponent has a sacrifice outlet (which they sometimes do). Deathrite Shaman also works nicely against decks that use flashback. I think it's a good metagame choice -- I agree it doesn't drive your main plan forward, but it does too much to the environment to leave it out for now.
I like the deck, thanks for picking it. Even if I disagree on your decisions, I like the discussion.
Isn't hellhole flailer just a bad geralf's messenger? I know 17 black sources doesn't mean you'll be running him out turn 3 every time, but the power difference seems worth it.