Upload & Sell: On
Just looked at photozone's review on the 16-35/4 and I see what you mean - resolution barely makes it out of the 'good' category apart from the centre, and around 21mm is the best it can do. Sad for a costly well-made pseudo-pro lens, with a huge number of elements and fancy glass, a similar spec to the 14-24/2.8.
Nikon don't seem to do corners well in wide angle zooms, as the 14-24 is similar in this respect at more usable FLs (20-24mm) but somewhat better. It does weigh like an anchor, flares, no easy fit Pol/NDs. Looks like a terrific 14-18mm however. I see your reasons now on refresh..
Maybe look further and be patient? A good ebay dealer in east Asia? Being in Aust I use them and have had very good results and prices...local to you, photo.net, a wanted ad right here (the 21mm is not everyone's cup of tea), getdpi, camera west, Nikon sites (Nikonians, etc.) good luck with it/.