Hi!
I still play on EU so the buff isn't here yet. Currently sitting at 32% haste (but still crap ilvl weapon) and I think this build might be the best single target + aoe build.
Talents are: Demonic Calling, Implosion, Hand of Doom, Grimoire of Synergy and Demonbolt.
The thing is to only use Dreadstalkers if you have the Demonic Calling buff. Also right after casting a new Hand of Gul'Dan use Implosion. You have about 13 seconds do cast another Hand of Gul'Dan which is usually enough. Always use Demonic Empowerment after Dreadstalker of Hand of Gul'Dan (after Implosion that is).
Wonder if you guys get similar results.
Edit:
Here is the WA that I made that helped me a lot doing the rotation:
http://pastebin.com/hHUHebam. Left marker is use Dreadstalkers, Right marker is use Hand of Gul'Dan (if it's saturated it means you are sitting on 3 Soul Shards).