Well-balanced, real review. Thanks Justin. I also like how you throw in you personal biases (your 24 TSE sidebar), it let's us know your approach to shooting and why "you" may or may not like something about a lens.
It's interesting how we photographers all have our own needs, which evolve over time.
I've owned both lenses, 17-40mm & the 16-35mm (which I still own...but would kick to the curb if Canon ever delivers a 14-24mm like the Nikon! LOL!)....I only owned the 17-40mm for about 2 weeks (it was the 1st lens that I had purchased after my kit 24-105 that came on my 5DII).
The one thing that really bothered me immediately about the 17-40mm (something I feel that Justin missed), was the "short throw" on the wide end of the zoom ring..say from 17-24mm. There is almost no throw. It feels truncated and abrupt...so that when zooming to the wide end I had no latitude to adjust my field of view. That REALLY bother "me". The lens did not seem well-balanced because of that factor. Also, I found the softness at f/4 to be disappointing. I ended up shipping the lens back to the seller for a full return of purchase price (something I have never done since with an L lens), and purchasing the 16-35mm L II. Although I gulped on the price, as Justin reports, I found it to be a better lens in every way and I never looked back, (my retirement fund may have,though ).