Ok, I've had a couple of more hours of shooting now and have taken 500 images, mostly of junk subjects, but practicing my technique. 90% of the shots are in focus and around 70% are what I consider super-critical focus, meaning an eye is still sharp at 400%. That's includes a bunch of shots taken with multi-point enabled with 5, 9 and all AF points enabled, as well as single-point AF.
As good as it is, you can't simply turn on all the points and fire away. I think that I'll be using single-point AF most of the time.
Here's a hand held shot with the 500mm and the 1.4x TC, yielding 700mm:
Untitled by
dcstep, on Flickr
Click on the image to go to Flickr to see the Original size, which I'll enable for a couple of days.
It's a big, big improvement, but there's still room for the photographer to make a difference by using good technique.
Dave