I have the Kirk collar and foot for the 80-400VRII and it is rock solid. It also provides a good carrying handle. The only downside is that it is not possible to reverse park the hood on the lens.
I'm wondering if Nikon changed the hood or Kirk changed the collar. I had this combination and the hood fit and locked in reverse position without problems.
Even with the Kirk collar (which does make the lens more stable on tripod) I still experienced blur with the 80-400 AF-S due to shutter and wind at focal lengths from 300mm to 400mm. Up to 200mm results were good, however. With some other lenses of similar focal lengths (up to 400mm) I have obtained consistent results using the same tripod and head though admittedly a more rigid tripod would be better for 400mm slow shutter speed work.
The 200-500mm has even greater angular magnification at 500mm and it is not clear how far a Kirk collar would have to extend its frontal support fork. I suppose the point where the transportation zoom lock is. To allow rotation to vertical orientation the frontal contact point could potentially scratch the "LOCK" markings, unless some kind of soft mounting (rollers?) is used. Here is an image showing the switch panel and transportation lock:
http://nothingwired.com/nikon-24-70mm-f2-8-vr-24mm-f1-8-200-500-f5-6-fx-lenses-announced/I hope Kirk is able to figure it out for the 200-500mm. Still, I find it objectionable that every time Nikon brings out a new telephoto lens, one has to wait for third party tripod mount availability and then pay extra to get what should be supplied with the lens.
I agree that it would make things easier if the collar area on the lens barrel were wider. The 200-500 collar is very narrow compared to the length of the lens.
