Other pressing commitments, plus the usual arrival of poor weather immediately upon my getting lenses for review, have delayed my work with the 200-500/5.6 for a while. Hopefully tomorrow I'll be able to spend an entire day in the field with 200-500 and the new 600/4.
Speaking of which, here is a direct size comparison between the two newcomers. I am loath to assign "kid" to the 600/4 though, as it completely dwarfs the 200-500. Do note that the 200-500 does extend about 1/3 more when it goes to 500, but it rapidly creeps to 200 once stood on its own. Nonetheless, the differences in size, and commensurately, their asking price, are huge. In fact, the 600/4 requires a financial outlay the equivalent of a small car ....
Evident also on this picture is the very different approach to tripod mounting of the two lenses. The 200-500 has a very narrow rotating collar, and to exacerbate the stability issue further, the tripod foot is slanted 45 degrees. This cannot be expected to yield a stable platform for tripod use and indeed test shooting with the lens at slower speed easily leads to a major loss of image quality. The tendency for the lens to make "swimming" movements is even more apparent once the new TC-14E.3 is attached to it. Do not be duped by reports of the 200-500 having a satisfactory tripod arrangement as they are quite misleading.