A lot of stuff has come into the inbox as to why the 1D X has been delayed yet again (Canon has yet to make it official). We're hearing a late June or early July arrival of the camera.
The latest and best information I have says the camera is delayed due to issues with an accessory. It could be the wifi add-on for the camera.
1D X autofocus performance
The good news is the AF system on the 1D X is being called the “best” and “fastest” system on any current DSLR, this includes the new Nikon D4 and Canon 5D Mark III.