"... the new firmware allows cross-type autofocusing with the center AF point when the maximum aperture becomes as small as f/8."
Am I reading this press release wrong? Why only the centre point when users like Arthur Morris have found that the non-centre AF points work fine at f/8 with Kenko teleconverters? It seems that third party or contact taping might still be the preferred method for many users. Surely all Canon had to do was to get rid of the protocol that disables AF beyond f/5.6 and warn users that AF might not be as reliable?
"I was able to toggle through the various AF Area Selection Modes. Then I pressed the edge of the newly designed joystick; stunned times three. Not only did the 1DX focus with the the Kenko Teleplus PRO 300 DGX 1.4x AF Teleconverter, I was able to move the active AF sensor." http://www.birdsasart-blog.com/page/3/
I should perhaps clarify that this is all based upon Art's blog entry; I have not bought his 1D X user guide (as I don't own a 1D X!). Perhaps Art and Canon have different standards for AF reliability; maybe Canon are concerned about low light reliability, or possibly they are scared of bad publicity following the 1D(s) MkIII AF debacle?