How glad am I that I sold my 24-70 f/2.8 L and bought the 17-55 f/2.8 IS? Very!
So, are these the first "L" EF-S lenses?
It looks like a Super-35 frame is almost identical in size to APS-C. I wonder why they didn't go with the EF-S mount. That would have helped the optical engineers designing the wide angles...