[mst]

Thanks M, you're testing it on DX also?

Sure.

If i got to shoot this at F8, then why not get a 20/2.8....

Well... if you limit yourself to a single focal length and aperture, yes, this may make sense. All others probably prefer to also enjoy the flexibility of the focal range (18-19mm and 21-35mm), as well as apertures of f/3.5, f/4, f/4.5, f/5.6,...

Regarding the 16-35/4 VR: as Klaus already mentioned, it's a more challenging design because of constant speed (f/4), a wider zoom range (don't underestimate those 2 mm) and better build quality. And in addition, it features VR, a quite rare feature in this lens segment. You may of course argue if you really need optical stabilization in a wide angle lens, but if you belong to the (likely limited) group of shooters with a use case for this lens, there's no alternative.

-- Markus