I used to have a Nikon 600/5.6 AIS that I had converted to AIP (i.e., chipped) by Roland Eliott, but at some point, I decided that manually focusing a 600mm lens on a gimbal head was not for me.
I just received the new Nikon 200-500mm/5.6 last Wednesday, but have not done anything with it other than take it out of the box to attach a QR plate on it -- been too busy and it's been in the high 90's / 100's here the past few days.
I might drive out to a local lake for some birding later today before the sun goes down and/or at sunrise tomorrow.