I've had two TC-200s. The first was stolen with my camera bag. I replaced it, and that should tell you something.
My basic Nikon kit is 24, 55, 105, 200 so having a 2x TC makes little sense on the face of it. I've used it mainly on my 200/4 MicroNikkor AIS, not the sharpest blade in Nikon's kitchen. When 400/8 makes photographic sense I use the combo and don't feel deprived.
Kino, whether a 2x TC makes sense for you depends on your lens kit. If your focal lengths are spaced like mine, 2x makes little sense.
As has been mentioned above, Nikon recommends the TC200/201 for lenses no longer than 200 mm and the TC300/301 for longer lenses. Both were reviewed very well when first released.
I also have a Vivitar Ser. I Matched Multiplier 450/4.5. I've used it, also my TC 200, on a 700/8 Questar. This is a difficult lens to use because of its focal length, which punishes the least unsteadiness severely. The TC200 worked a little better on it. But 1400/16 is hard to focus and even more susceptible to vibration, subject movement, focusing error, ...