ask the wu jian dao flipfreak bro..
personally, 1DX is really tok kong. My quick 15mins play already can notice the improvements over 1D4 liao.
i am just a user. i got no idea why they are still very hush hush abt it.
the 1d4 is a really nice camera too. i shot some side by side pics with the 5d3 in jpeg and it has very clean images as well.