Nikon d810 and D4s AF compared in low light?

haring

Is there a photographer here in the forum who has both the Nikon d810 and D4s? I would like the hear a real life experience regarding AF performance in low light?

I know that the 810 is capable only 5fps. I am wondering whether the AF in the D810 is as fast and accurate in low light as the AF in the D4s?

Thanks so much!