to be honest i see ABSOLUTELY NO benefits in going haste/crit over pure crit on zerg comps.
to experiment a little i went full haste and only gained .1 sec off a divine light cast. goign full haste may give you an extra tick throughout duration of Eternal flame, but you always are renewing it so that doesn't matter either in my opinion. why waste so much crit; which gives you so more instant heals such as 3point WoG and fast casts.
on zerg comps you want to run Crit>master>spirit.. there is a fine line of how little spirit you want to have..every reforge goes into Crit. and mastery and spirit has to be balanced. thats based on how well you generally do w/ your mana
on caster comps or melee/caster you tend to have a preference. its iffy atm due to the new gear but i know for the most part ppl really enjoyed Crit over mastery. its preference. i choose Crit, i think crit this season will be even better due to higher stats. if you reforge full crit you should be along the lines of 36% with buffs. add the 25% crit from HS (61% total on HS) once fully geared. you should basically get a quick cast proc all the time.
but it should go Crit>spirit>mastery>haste or Mastery>spirit>crit>haste.