Quote Originally Posted by Scott Stephen View Post
Exactly. What can one point to that is more appealing in the 17-40 vs the 17-55 2.8?
-You are not trying to "go full-frame", so the EF-S mount is not an issue.
-The aperature is smaller.
-The zoom length is shorter.
-The IQ is poorer.

Other than weather sealing, I can't think of anything, and frankly when it is raining I photograph indoor things.

It seems one would have to be one heck of an outdoor-oriented photographer (living in one heck of a rainy place) to value weatherproofing over all the other factors above.
Or snowy.

cls stated the same thing a while back and you have summed it up well... it is about weather sealing, and that only maters when you upgrade to the 7D which has better weather sealing in the body to allow you to take advantage of the weather sealing in the lens.

FF seems to be out of the plans - so that doesn't matter.