I've had the opportunity to use the 7-2f/4IS and 7-2f/2.8IS for a collective couple weeks each. I've finally settled on the f/4IS ( I hope ). With all of my testing, I never got any ducks, so I went out today 
It was a little bright and I didn't edit these files aside from crop and resize so they're basically "out of the camera".
30D, 70-200 F/4 IS, B+W MRC UV filter, and all but one with a Canon 1.4xTC.
Original files here: 1
, 2, 3, 4, 5
Only the first image is without the 1.4xTC:
The nerve of this tree...
Ya, he's ugly..but was a willing subject
Mom had enough of me I think..
The only two gripes I have with the f/4IS is I don't feel it focuses as accurately as the 2.8, ie, smaller subjects and further distances, and sharpness at further distances...as this is known anyway. I'm over the 4vs2.8 fence, I think I only have one hand left hanging onto it now...lol.
