After taking a few thousand more images with the 70-200mm, many with the TC-17E, I just have to reiterate what I wrote in my review: "no complaints about sharpness with this lens, even on a D3x, even wide open, even in the corners once we close down a stop or two." If anything, I'm slightly more impressed after this latest round of field work: even the stuff I took with the TC-17E looks quite good (as usual, Nikon's newest goodies, such as the TC-20E III, didn't make it to me in time for my trip).
I was also impressed with the way the lens performed for focus, again even with the TC-17E attached. I threw some tough situations at the combo and didn't really notice any degradation in focus performance. Indeed, I was surprised in a couple of situations where the camera didn't switch to busy backgrounds while tracking motion diagonal to me.
For FX users, the new version is pretty much a dream come true (except for that focal length breathing up close). If you've got an older 80-200mm or 70-200mm on your FX body, you should try the new one--I think you'll be surprised at how clear the difference is. On the other hand DX users won't see a big gain, if they see any gain at all. So if you're still using the older 80-200mm or 70-200mm on your D300, don't get jealous, just keep taking pictures and think about the money you saved. But FX users need to take a long look at the new lens even if they are happy with their old one. The differences really do jump off the screen at you with a D3x.