Wow Doug, that is a great difference. I don't know if it is my imagination or what, but since getting my MIII I don't see the same sharpness when I use the 2x II. I look at old images from my 40D and 7D and the sharpness is so much better that I wonder if it is a combination (2x and the MIII?) I'm kinda bummed about it. Your article was a great helping deciding to get a new one.
The 1.4 new version I used this weekend and even on optics not supposed to show any improvement there was a noticeable improvement to IQ and focus speed..