The value of crit is quite often underestimated for ele in pvp. Definitely for boxers: lets say you play 4 ele shamans, who each have 20% crit chance.
When you cast the same spell on all 4 toons, then the chance that one crits is:
[(1 - (0.8*0.8*0.8*0.8) )*100]= 59%
When you spec into acuity, this changes into 65%, which outweighs the extra damage gained from elemental precision by miles. It's not even a discussion that acuity > elemental precision in full ruthless gear. You can easily reach the hit cap and still have decent mastery & haste values. Into 4.3 where the flametongue imbue gets replaced from a flat spellpower value to a dmg buff, the value becomes even bigger.

If you swap around other talents, that is up what you do (bg/arnea) and to your playstyle/comp.

Not really related to boxing, but there was an interesting discussion on skill capped the other day about crit. One of the better pvp'ing ele shamans out there made a claim that he prioritized crit over mastery and haste for arena. He never really explained in detail why, but there were a couple of interesting reasons being discussed why that is. My theory is that it mainly depends on the comp you play. I've seen ele's who mainly shock / kite all the time rather than hard cast, trying to create a window of opportunity by cc to burst hard with fs/lvb. If you find yourself shock/off healing all the time, a pure crit spec becomes really interesting.