Gregg: The 17-55 may not be 'L' but have you seen the pictures? Many reviewers say it is absolutely L quality. The quality of the 17-55 2.8 is through the roof. It's the weather sealing that breaks the L deal but in terms of image quality I was blown away.


Check out the review:


http://www.the-digital-picture.com/Reviews/Canon-EF-S-17-55mm-f-2.8-IS-USM-Lens-Review.aspx


Let me quote: 'As it turns out, my 17-55 matches or exceeds the optical performance of my L-Series zooms in this similar focal length range ...'





So it is well worth the price and investment. (And I am sorry to say but I didn't think the Tamron you mention in your post is nearly as good as you make it out to be. It's cheaper, but the quality is far less than the 17-55). (And yes, I had both lenss when I shot with a crop body). Just my two cents.