I have the original and it's a great Lens.
But since getting the 100-400II I am liking how sharp and crisp the images I am getting with that.
The original 24-70 I have is pretty nice, but just lacks that real sharpness and crispness the 100-400II has. Don't get me wrong... it's pretty sharp, but just not as good as the 100-400II
I have read some reviews and they say the difference is marginal, and other reviews where that say it's the best thing since flush toilets.
I would be interested in what you guys think.