maybe i am old school, but i will not buy a lens that is not internal zoom. that is why i have waited to buy a Canpon lens in this range all these years. external zooms, to me, make the lens look cheap and amateur, not to mention all the weather and dust issues. i would gladly pay a reasonable amount more to have all the movement happen inside the barrel.
i own the 70-200 2.8 II and the 16-35 2.8 II. but the 24-70 2.8 always seemed rinky-dink to me, regardless of how good the image is.
of course, i am not saying make the lens less sharp to make it an internal zoom, i am just saying, keep the sharpness, but enclose the darn thing. olympus does it with their beautifully sharp 14-35 (28-70 equivalent on the 4/3 format), why can't you?
please, Canon, don't let me down on this...