OK, here gos..
Found that + 2/3rds in Centre Weight, on Sigy 150-500 was not to bad at f 6.3 to f8 .
+ 2/3rds on the 400 f5.6 Blows out the highlights. 0 (zero) in Centre Weight is better. More adjustments to do there. Will try Pattern tomorrow (Evaluative).
This lens is so silent with no movements that at times I thought it was not focusing. The 100-400 when focusing you can feel it on the camera slightly.
It is Fast on focusing but I still had a lot of Blurred birds in flight and near the feeders. Only used single-point af and af point expansion (5 focus points) today.
AI Servo with back button focus is what I use.
If you use anything else you think is better, please do tell.
My left arm ached after a while which don't help me any as I get pains in it all the time.
Now then, YES! I did get some nice sharp birds that even looked sharp at 100% pixel peeping. Whereas the 150-500 was SOFT, SOFT.Yuky. lol
I tried iso 200/400/800 and f5.6 to f6.3 to f7.1 to f8. I did have some slow speeds, my fault for not concerntrating enough.
Now I really need to practise. All in All, I'm quite happy at this time.
Will I still be happy by Monday

(Off out again tomorrow).
We will have to wait n see.

It is a very nice solid lens. Cost £919.
I got a USA & Canada Warranty though, so I might phone Canon next week to see what they say. Ian Kerr (Kerso) does give you his one year Warranty though. So far i have had EXCELLENT service off of him and I do recommend him if anyone needs a lens. Best to email him as you get your gear a bit cheeper that way.
Golly, my Camera insurance is gona go up with this lens. Already £144 a year.
Need to sell my Sony gear soon and that 150-500 as I want my 70-200 f4.
Must Register the lens to see what Canon says.
That's it for now.
Take Care.