> Therefore, buyers of the Canon Rebel, 70D and 7D series should have a serious look at the 17-40 as their “middle” lens.
Disagree. The last several EF-S 18-55 kit lenses are significantly improved over the earliest versions. You are paying "L" prices and paying for full-frame coverage on a crop-camera.
The EF-S 18-55 is much lower cost (almost free as kit lens), lighter, possibly sharper, wider zoom ratio (40mm vs 55mm), and has good to very good IS.
Granted, the 17-40 has fixed f4 and better build quality.
I really can't think of a situation where I'd choose my 17-40 on my T3i/600d over my EF-S 18-55 ... unless I had the 17-40 along, and didn't have the 18-55 with me. I probably ought to sell my 17-40 ... I almost never use it.
I did get a Samyang 14mm, and have been Very Happy with it on full-frames. Amazing bargain.