I'm an American living in Beijing. I have a D300 and a Nikkor 70-200mm f2.8 VR lens. I bought the Nikkor TC14E II about 6 months ago. I read a review that it was amazinly sharp in combination with the 70-200mm f2.8 VR. It was. Now having bought the TC17E II, I wish I handn't bought the TC14E II. I think I will only carry the TC17E II, so I may sell the TC14E II. Not that the TC14E isn't super sharp (it is), but I don't need both, since they are so close. Once I find out how good the TC20E II is, I may end up with the TC14 and the TC20 and sell the TC17, since I think all three is overkill.
This review is not based on a lot of shooting, but I am very happy with the TC17E II. I saw that no one else had written a review, so I thought I should try to contribute something, even though preliminary.