But I don't understand why people need a wide angle with F2.8. You don't do portrait with a wide-angle that had "by nature" some distortion.
You use the wide angle at F8, 10 and more.. so why bother and pay for a "new" f2.8 that would be heavier and much costly... New versions cost always a lot more with canon.
I'd like my 8-15L f4 to be a 2.8. iso 3200 vs. 6400. Big difference.