Bit of a dilemma ATM, just got the new 24-70mm f/2.8L ii a couple of weeks ago and I've been doing some testing with it up against my MKi. So far I'm yet to see any significant difference and if anything the MKii isn't as good the the smaller apertures!
At around f4 to f11 the MKii has a very, very slight advantage in the sharpness but it's minimal. When I first got the lens it was front focusing so I sorted that out with some AF Micro Adjustment but after the latest batch of testing I'm not seeing any reason to sell on my MKi.
Has anyone else had any similar issues or had to take the lens back for a replacement?
I can post some 100% crops or example images to Flckr if that helps?