I actually built a deck with the same premise as your original build, the other day. Admittedly though, I feel yours may be a little more competitive than the one I built. The only thought I have is to essentially add an additional vote to dropping in the
Void Winnower. The card's ability breaks the game for your opponent and demolishes a vast array of strategies. Tokens, white weeny,
Collected Company, dragons and even a lot of control is effectively brought to a screeching halt due to their spell's even converted mana costs. I play one in an Eldrazi deck I built and it both shuts down and wins a lot of games. If I was to suggest a card to drop for it, I would suggest Kozilek as though a great card and a great bomb it's effect is lacking if not cast. Just my thought though. The deck looks really good either way.