Hi David,
Welcome to the forums. I use the 7D and 100-400 L combo. I agree it works really well. Sometimes the AF isn't as fast as I would like, but it is still much faster than my other telephoto lens (an old 75-300).
A few recent pics from the combination:
Loon-7326 by kayaker72, on Flickr
HB-7412 by kayaker72, on Flickr
small-8036 by kayaker72, on Flickr
Thanks,
Brant