Dr Lens made me two TCs into AF-S extensions. This is the 14E.
I tried most of my lenses with both but not systematically or extensively. Could not find much use for the 20E yet. Clearly the 300PF seems to take the 23mm extension from the 14E best, offering a wide range of possible focus distances with good subject distance and magnification. Plus the qualities of the unextended are maintained well.
Next will be hunting bees in flight. You know that this is a hobby of mine...
I do not see much difference between D600 and D500 yet. The D500 FOV is a tad on the narrow side for my taste though. Above examples are taken with the D600 offering decent AF with this extension on the PF