@Rover: The different focus was depending on the Sigma in LiveView* and handheld and the Nikkor normal AF and handheld. I had no tripod with me at this Sigma testing day. It was - as you noticed - a quick and dirty shot. But I don't want to shoe the sharpness difference between the two lenses (which is visible wide open) but the massive ammount of LoCA of the Nikkor.
However, the Sigma 85/1.4 leaves only two things to the Nikkor: less weight. smaller filter. For the rest it rips the old Nikkor into pieces. Menawhile, the LoCAs became very hard to accept to me as I know today, it's possible to get a lens with much less of this flaw.
* at the event I had problems to adjust the Sigma's AFMA correctly, that was a reason to go into LV. +20 was not enough and I had no dock with me to correct better. I lateron told the distributor that I'd be careful to put this copy to rent. If one doesn't know how to adjust and how to use the dock, that copy will make customers unhappy. He didn't care - I got the same lens lateron to rent and it took me a while to adjust.
That Swiss distributor sits on a high throne, he's relying fully on Sigma's great quality while the quality of his own services is either expensive or poor or both.