Just posted a new blog post where I play around with Haste Breakpoints of our DoTs to get to the bottom of why Haste was under performing in our stat weights. In short: below the SWP-2 breakpoint, Haste is king. Above, it really doesn't matter if you go Haste/Crit/Mastery.
Below SWP-2 Haste Breakpoint (8085 Haste)
Int > Spell Power > Haste > Hit=Spirit > Crit=Mastery
Above SWP-2 Haste Breakpoint (8085 Haste)
Int > Spell Power > Hit=Spirit > Crit=Mastery=Haste
If you want to look at the guts of the post, it's over here ---> http://warcraft.twintop-tahoe.com/?p=205