I know this thread has been long-dead, but just in case someone considering Whole30 finds it in their search, here are a few comments: I'm almost at the end of my first Whole30 (after 12 years of primal). I've found it very useful, because it helped me realize how dependent I had become on cheese as a quick meal-substitute, and my nightly bourbon.
Some points to clear up:
a. It's not at all low-carb; the moderators on the Whole30 forum are constantly harping on people to eat more, more, more starchy veggies, especially sweet potatoes and winter squash. And fruits, which are also hardly low carb.
b. Ghee is strongly encouraged, so you can eat all the butter-fat and its associated good vitamins and oils as you like.