Well, in defence of early adopters, if I had bought the 300/4 PF at the Jan/Feb when I had a chance, I would have been using it and enjoying it for 4.5 months by now. Instead, I'm waiting for it to be available again. So, early adoption can have its merits if there is a product that gains a very favourable reputation then there can suddenly be a huge increase in demand and the lens can't be easily found in a long time. I got to use a friend's copy for a few hours and I was very impressed. It is so much fun to use and the autofocus (with D810) tracks moving subjects silently and with unusual degree of perfection. I think this is a breakthrough lens and should be very good for Nikon's market share once the word gets out and the supply catches up with demand.
Thankfully my 200/2 II and TC-14E III seem to like each other very much at f/3.5 - f/4; so it can be said that I don't strictly speaking
need the PF. But for many applications a compact lens is preferable. I find it surprising that Nikon would take so many years to make a revision to the 300/4 and then be taken off guard by the demand. I find the 70-200/4 also to be a great lens; fun to use and produce images of very high quality. I imagine these two lenses will be sitting next to each other on many trips in the future.
I'm a big fan of large aperture lenses in general, but at long focal lengths they are a project to lug around, even though the images from them are a delight to view.
So it is good to have a slightly smaller aperture option.
Of course, there are sometimes issues with early copies of a product; in the case of the 300/4 PF, the VR glitch (which is a significant issue to some users but not for the way I would use this lens) but I've bought many Nikon products when they came out and had no issues. So it's not guaranteed to have problems. ;-) Usually the price does go down gradually after initial demand is met, but that is subject to changes in economy; sometimes the price can go up.
By the way, has anyone yet used the TC-14E III on the 300/4 PF? I'm curious as to how the performance is.