I've got 2p T12 and 2p T13 - waiting for shoulders/chest to drop (I have the T13 gloves).

Anyway, my question is; is Crit superior to Haste after reaching the VT haste plateau? As according to a guide I found on shadowpriest.com, Crit is above Haste (with 2p T12, of course), while the plateaus are still worth going for, but everyone keeps saying Haste is superior to everything all the time. Can someone tell me what's actually going on?

Also, another thing I'd like to know is the Haste plateaus in percentages in order to figure out at what point Berserking/Bloodlust/Power Infusion gives me more ticks. I get Dark Intent, a couple of Power Infusions, and I'm a troll.