Thanks for another nice review, Justin. The single biggest factor for regarding these two options is purpose. If someone wants to do creative wide angle work at maximum aperture, the 17-40L is not your choice. If you primarily want to do landscapes, though, the 16-35LII and the 17-40L are very similar when stopped down.
I own a 17-40L, and I don't love it, but I also haven't yet found a replacement that makes a lot of sense. It does produce really nice images, focuses well, and has good color, but it just isn't amazing. I like doing LE work sometimes, and the 77mm front element means that I have plenty of filter options, which just isn't true of something like the Tokina 16-28 or even the mighty Nikon.