Much better than 17-40L is Tokina 16-28 f/2.8 at the same price.Oh come on. The 17-40L would be way better overall
+1 You can't argue with this. The 17-40 is a professional grade L lens. I've had one since they first shipped nine years ago. It's been in daily use ever since in a demanding client environment. At $500 it probably won't last long. Snap it up. You'll easily make your money back in the unlikely event it doesn't work for you.