Update 23.04.2016: Balancing the 600mm FL horizontally works fine now. I finally went with a foot replacement by jobu design.
Update 06.11.2015: A few words about my setup in the video. I replaced the stock foot of the lens with the RRS LCF-13, which has a lower profile, is lighter than the original Nikon foot and even slighly longer. The tripod head is by Dietmar Nill and weights 1.2kg. Unfortunately height can not be addjusted, but it’s less extrem than it seems in the video. Note that the exact same setup worked perfectly fine on the older 600mm F/4 ED VR.
I just got my Nikon 600mm f/4 FL ED VR a few days ago. It’s so light and you can really handhold it. But the initial smile after picking it up went away pretty quickly as soon as I mounted it on my tripod with the D810 attached. It’s not possible to balance it! It’s way too front-heavy.
Only after not only attaching the additional battery grip MD-12, but also loading it with AA batteries, did I manage to balance it. The normal EN-EL15 was not enough.
How can this be? What an oversight by Nikon! I bought this lens because it’s light, and now I have to add weight back to make it work properly. What an irony!
This actually means that it only works properly with the heaviest camera, the D4. It also means that Nikon can’t make lighter flagship bodies in the future as long as they still want to support this lens.
The only solution I see without having to completely redesign the lens, is to drastically reduce the weight of the hood. Good opportunity for any 3D printing business. I’d buy one.