Originally Posted by
Alzu
You think this and think that. How about wrathcalcs? What does it say?
Losing 200 crit and 300 haste for 500 mastery is less than 200 dps loss in my gear. The gain from the set bonus is 1100 DPS in my gear. Even if somehow magically yours would yield highly different results, the difference wouldn't be major enough to let you keep your non-tier helm.
Mastery, while being the worst stat, isn't something you'd need to avoid like a plague. Besides, the 4set makes your life much easier in multidotting scenarios.