Anyone using a Canon 200-400?

[Morgo]

Hi everyone,

I'm considering buying the Canon 200-400 for an upcoming safari in Botswana this year.

I would be really keen to hear from anyone who has used or owns this new lens, especially how it compares to the 400 2.8 IS and 500 f4 IS models (not the new IS II's) in terms of AF speed, IQ and sharpness)