I will say now, after having shot a soccer match tonight, that the 400 f/2.8L II IS auto focuses MUCH faster than my version 1 I had. I had 615 razor sharp photos, which is way too many but that was not even possible with my version 1. Well worth the cost in my opinion. Great shots to all who have posted here and I plan to keep contributing. Thanks.
That's interesting, and good to know. Do you think it's the same with the 300 2.8IS and 2.8ISii? I sometimes think my 300 2.8IS isn't as fast to AF as my 70-200 2.8ii.
Agree this is interesting, as I haven't read/heard this before (I mainly go to TDP for reviews).
As for the 300mm MkI and MkII lenses, I did not notice any major differences in AF speed on my 5D3 when I tested them back to back a couple of weeks back. Since MkI lens left my home together with it's new (and happy) owner earlier today, I am no longer able to do an actual test for you, sorry.