This will be true post-2.1 as well since both shields have proportionate increases in Armor value. This is a very simple explanation on why the Azure Shield is better than Sha'tar, to put this argument to rest once and for all. It's found in the "Effective Health" thread on the US Warrior forums.

The Crest of the Sha'tar vs. the Azure Shield of Coldarra
It's a good discussion. I wanted to throw one other practical thing into the mix. A question I still see regularly asked is whether the Crest of the Sha'tar or Coldarra Shield is better. Hopefully a quick comparison should help tanks with the decision.

Through some arithmetic, I broke down the number differences between the two shields, assuming the Crest of socketed with double +12 gems.

Crest of the Sha'tar
140 Health

Coldarra Shield
203 Armor, 14 Block, 9 Defense Rating

Joe Tank
I'm going to throw in some average numbers a tank should be achieving with Heroic-level gear. I'm going to use two sets of health stats, one party buffed (13,000) and one buffed with some consumables (15,000).

On the next two parts, I'm adding the differences in Armor/Health to the above and running the equations from the first post in this thread. Note that the Armor value does not matter and could effectively be much higher or lower with no impact on the shield choice.

Effective Health with Crest:
13,140 Health
12,000 Armor (2.132 : 1 Conversion)
Total Effective Health: 28014.48

15,140 Health
12,000 Armor (2.132 : 1 Conversion)
Total Effective Health: 32278.48

Effective Health with Coldarra:
13,000 Health
12,203 Armor (2.155 : 1 Conversion)
Total Effective Health: 28015 -- Superior to Sha'tar

15,000 Health
12,203 Armor (2.155 : 1 Conversion)
Total Effective Health: 32325 -- Superior to Sha'tar

Additional Benefits: 14 Block Value*, 9 Defense Rating

*Keep in mind that Shield Block Value follows all the same rules and provides all the same benefits as Health does for every time you block before being healed to full (even just one block provides a benefit). Bear in mind that Shield Block Value increases with Shield Mastery as well.

The choice is yours between the two shields, but this should clarify a bit better the difference between them. Personally, I would take Coldarra or Nightbane's shield in a heartbeat. Then again, if the choice is between Coldarra or Sha'tar & Gnomeregan Auto-Blocker, my opinion might become a little biased. Cost effectiveness and what you are realistically doing in instances matters as well. :-)