Quote Originally Posted by Synomis192 View Post
I really do like the 17-40 f/4 though because if I ever felt the need to upgrade to FF i'd have a walkaround lens for the camera.
Actually, the angle of view changes dramatically when a lens is used on full frame. The 17-40 becomes an ultrawide, giving about the same angle of view as the EF-S 10-22. Most people wouldn't consider that to be a "walkaround" lens, though you can definitely use it as one (I did) if you like very wide angles of view.

The benefits of the 17-40 include great build quality, excellent autofocus, good manual focus ring, high resale value ("L" brand), full-frame compatibility, and good image quality at f/8. The downsides include a narrow f-number (f/4), high cost, and poor image quality at f/4. The Tamron 17-50 f/2.8 is cheaper, faster, longer, *and* significantly sharper at all f-numbers between f/2.8 and f/5.6.