Aaaarrgghhh!!! This choice is not getting any easier, but thanks for all the info and opinions.
I think I still like the zoom over a prime lens, just makes things more versatile. I, nor the missus, will ever be a pro photographer, we just want to take good happy snaps, rather than "See that black dot, that's a rhino!" type of stuff.
Here's two reviews of the 70-200 f2.8, both say it has less resolution and more chromatic aberation than the f4 version, at the same aperture.
http://photozone.de/canon-eos/199-ca...report--review
http://www.the-digital-picture.com/R...ns-Review.aspx
And here's the f4
http://photozone.de/canon-eos/196-ca...report--review
The 2.8 appears to have a lot more chromatic abberation across the board. The f4 also has better IS than the f2.8
Cheers,
Jason.