Thanks for the analysis.. i really cant justify the price.
For nikon teles i only own the 80-400 VR (pretty decent, i can get sharp shots handheld at 1/50 and its way more handholdable than 200-400) and a 300F2.8 (1.5X and 2X standby).
yea. but 80-400mm , AF aint that fast.