As many others have noticed, you need 25% threat reduction and 2 minutes off shadowfiend cooldown. The only other thing I would change is that you should probably get 5th point in improved mind blast once you get 10% haste (or 7% if you have a ret pally or boomkin). This will have MF at 2.75 cast, and mind blast at 5.5 cooldown. They sync really well and that's how I do it when I raid atm.