... on the 6d there is *no* cross point at all if you attach a lens with f2.8+ (i.e. fast zooms, most primes). It's no speculation to say that a cross point will provide more reliable af than only horizontal/vertical, no matter what magic you put in the firmware and how dark it can be.
Not quite true. The f/2.8 line is superimposed on an f/5.6 '+' (technically, the f/2.8 line pair is outside the f/5.6 lines). They act in concert. If the f/2.8 line cannot achieve focus, the f/5.6 line is used. Also, the f/5.6 lines are better with substantial defocus, so often with a hybrid AF point, a 'coarse focus' is achieved with the f/5.6 line(s), and that's refined by the f/2.8 line(s).
Okay, I've spent some time researching this tonight, but I'm still not too sure. So how is this cross type AF point on the 6D different from the cross type AF point on the 5DII or T3i?