I have to say that I am quite impressed with how the 11-24 handles flaring. The Buckingham shot above, as you can see, was pointed directly at the sun. Even when the light source is coming from a harsh angle the lens controls flaring well too. I used to have a Tokina 16-28mm and I always had to be very careful to mind where the sun in the sky was.
In the 11-24 shot of the Tours City Hall, there's a pretty harsh flare artifact you can see in the upper right corner, a couple of streaks and a bright oval just off the upper right corner of the building. There was a streetlight directly above the camera, just out of the frame. But it would be easy to clone out, and importantly the veiling glare is pretty minimal. The TS-E 17L is a little worse with flare than the 11-24 (I didn't have to clone it out of the shot, though - with the narrower AoV I am able to block the light source with my hand during the exposure without my hand being in the frame).
The flaring in your 11-24mm shot is still perfectly acceptable to me, and indeed, cloning it out wouldn't be too much of a problem. I've not used the 17mm T/S extensively enough (only once indoors, actually) to comment on its flaring, but your point is interesting to note. Taking account of the wider angle of view, I assume it's the new coatings on the front element of the 11-24 that are helping it along.
Unfortunately, bulbous front elements always have some trade offs . Another issue is the lack of simple screw-on filters. Despite that, though, the 11-24mm is a brilliant lens. I'm really enjoying my copy, and I might even go so far to say it's my current favourite lens.
Hope to see more of your shots while using it!