Guys, thanks for the 2x images, this definitely gives me the confidence to get this lens over the 100-400, as the 70-200 gives more flexibility and image quality.
Are you guys using the Canon 2x?
Mine is the canon 2x. I got it mainly to keep weather sealing, but I've also seen that the Canon 2x II seems to be a little better than the Kenko 2x. The 1.4x I have is a Kenko, which I like because it's just as good as Canon's, and I can stack it with my 2x if I really need to. I did that for the first time last night, but won't get to look at the pics at 560mm until later today. They looked decent on the LCD though.