This. It's only slightly less sharp. On 16x20 prints, you still can't tell the difference. However, since I'm a pixel peeker, I notice it.
the 24-70 > 24-105.

on sharpness maybe, but generally 24-105 has some advantages over 24-70, but it also has some disadvantages. which lens is better overally depends on the situation. i chose the 24-105 even tho i could have bought the 24-70

Not only that, but build as well. I've rented the 24-105 and its a good lens, but it is inferior to the 24-70. For my needs, F4 isn't fast enough. After messing with 1.2, even 2.8 is slow.

Nah mate. If you are spending $1600 dollars on a lens, you should expect it to be pin sharp at all stops. I'd get that thing calibrated. Having to shoot at f4 because 2.8 is soft defeats the purpose :/

I've heard the 24-105 is pretty spot on at f4.

Go buy a 5d mk II body instead...

haha well, if it ain't THAT far off then it's totally cool

He's got 2 man.

Lolwat. Last time i heard.. he's only got 1.

bought the second one. I should put an equipment thing like yours.

Because of the way a lens is built, it is, by design, less sharp at 2.8 than at 4.0 or 5.6. Any lens works this way.