I wonder if the 200-400 breathes and what T value it has.
It would still be the dream lens for safari if one has an unlimited budget, otherwise the primes look a little more interesting due to the very high price of the 200-400
According to TDP, the lens has a 0.15x magnification without the built-in extender. Presumably this is at 400mm with a focus distance of 2.0m. However, looking at the 400mm f/2.8 II, it achieves a larger magnification (0.17x), even though the MFD is 0.7m further away! That's a tell-tale sign right there
Investigating further, we see that the 300mm f/2.8 II has the exact same MFD, but a higher max magnification (0.18x). In other words, when the two lenses are focused at 2.0m, the 300 II will frame the subject more closely than the 200-400@400mm.
This implies that the 200-400's effective focal length is less than that of the 300 II at the MFD. According to my calculations, at the MFD, the 200-400 has a similar FOV as an ideal lens with a focal length of ~200mm.
Looking at the numbers for the big primes, they also do have reduced focal length at MFD (but less severe), so the 200-400 may still be a dream lens for safaris