>>31484125D3 also has awesome AF.
It's like comparing a Ferrari to a Lamborghini and complaining one is slightly less loud.
Calibration is an issue with all DSLR's, true.
It needs incredible precision, just a fraction of a millimeter makes a difference.
But you're making it much bigger than it is.
In the vast majority of cases it will be fine out of the box.
If not you can calibrate yourself or have it done.
And it has nothing to do with the speed or reliability of the AF system - that's something you cannot fix.
