Thank you for this eyeopener. It still makes my decision a lot harder again :P I hoped that the 17-40 wasn't that sharp so I could finally rest my mind ang go for the 17-55, but your comment makes me doubt again. Later this week I will try both lenses at my local store and I was nearly there to buy a 17-55. You got a 100mm macro that I have as well so you know what I mean when I say sharp. Thus if you think the 17-40 is sharp as well, I really don't doubt it. Also no I'm not planning to buy a FF camera, I like the 1.6 crop. Man this is a hard decision Still not convinced..