Now that I have owned and sold the 14-24, I think I'm now qualified to answer.
Let me preface that I had the 16-35VR for 3 years and loved it. Sold it for 18-35G because I wanted a lighter lens, and then sold it for the 14-24 because I wanted the best, or so I thought.
A big mistake. A confounding epic fail, if you will.
For the 14-24's first test, I took it to Yosemite. Within seconds of taking the first shots, I was greeted by flares...there were flares everywhere! And not just a simple flare, but the kind of flare that destroys the entire image. It didn't matter where the sun was - in front of me, above me, behind me, it would just flare. That was my biggest issue with it.
Then I started walking around the Merced River, where the great Ansel Adams have captured so many iconic landmarks in his time. I sat down and set up my tripod. Feeling inspired about the great framing and light that is about to shimmer on the unfolding scene, where El Capitan, Bridalveil Falls, and Merced River come into one. I reached for the LEE filter pocket and realized... "oh crap, this lens doesn't take filters!"
There I stood, bewildered.
I took a shot anyway, and the ever present flare manifested itself yet again.
"Ok, fine.", I said. So I took my rig and hiked the Four Mile Trail. There, I started to realize how heavy the 14-24 is, and how I constantly had to zoom in to 24mm to retract the bulbous element and protect it from Yosemite's wilderness.
Slowly, it dawned on me that the lens is actually a liability to my style of shooting - a detriment even. It's an event lens that is capable of shooting landscapes, but not the other way around.
On the way home, I looked at the 14-24. It was staring back at me, with its bulbous element exuding that arrogance as if saying "I am the best wide angle there is on the planet and you will never get rid of me". But I didn't care. Oh no I did not. In my mind, you are overhyped. An overhyped lens that is a product of the internet, where gear heads lurk who want nothing but the best, yet disregarding actual shooting conditions.
I arrived home and humbly packed the arrogant lens, off to its next owner.
I then acquired another 16-35 and I instantly felt like I was reunited with a long lost friend. Welcome back, 16-35VR, I will therefore wrap my arms around you tightly and never let go again. Good riddance, 14-24. At least I have lived with both and I can honestly say that it is the 16-35VR that I'm in love with. Oh the horror on the perfectionists faces.
A parting shot with the 14-24 and D800E. Yosemite Valley, September 2014.