I'd like to see more examples, especially shot with the 7D. His shots with the 17-55 seem to be very soft for that lens, at least compared to the three different copies I've used.
No it's a fine copy. Best of 4 in that time period I had. Realize that under controlled conditions w/o harsh lighting (like your shot), one can make any lens look pretty good. Distance to subject makes a huge difference too.
Point is: it's not appropriate for one person to take a shot, show the 100% crop, and then compare to another person's crops, and make any conclusive statement. I am comparing my 2 copies at the same time and same place under same conditions and same subject distance.
I am sure you're enjoying the 17-55. I never said it's a bad lens, not at all. It's quite good. Just not as good as the Sigma.