I'd like to call foul on how you're rating the Crown Chakra.
The Natural Armor provided is NOT an Enhancement Bonus, and would therefore stack with the (typical) Natural Armor booster (the Amulet of Natural Armor). An effective extra +3 NA at level 1 is very nice. At level 8, when you pull out a +5 to AC? That's pretty good.
It's less awesome on a race with it's own Natural Armor, but it stacks with the item.