I have a few playtesting questions:
When do you decide to play conservative and do the untap thing (eot) in order to increase the potential certainty of going off?
What kind of oppening hand is good enough (keepable) vs a deck with 4 force and 4 manadrain?
What do you sideboard out for the xantids and does that change with different machups, more importantly, why?

I also have some maindeck choice questions:
Is there a way to put xantids in the main without taking to much from the power of this deck and would this be a good change?  

Oddly enough, I think that this question is best answered by how prepared your enviroment is to welders than anything else. That being if welders are running rampent, then the natural answer is anti-welder cards, which also kill xantid.

With the recent successes this deck has had and it's vault into the mainstream articles, would a secondary win condition like colossus be benificial because of the possible increase in stifles present.

By the way, great report and thanks to anyone that answers.
edited once thus far for spelling stupidity.

Dream Halls is not a good card.  It was the basis in a deck that was ridiculous, and that's it.  It's restricted because no one wants to see that deck come back, ever.  It's not restricted because it is too powerful and shouldn't ever be played in serious Magic.

Xantid doesn't deal with Null Rod, Trinisphere, or Chalice.  Those cards wreck DeathLong a lot more than Force of Will and Mana Drain.  You can play through those without too much difficulty.

And with that, this thread is swaying off topic.  I agologize, but I had to chime in on this one.