Poppies are such wonderful subjects for test-shots: Their stems have very fine hair!
Here are some first observations from comparisons side-by-side on a D300 DX body with the Nikon 50/1.4G seem under controlled conditions.
to confirm what the MTF-Charts indicate: the new 1.8G lens is a little sharper/contrasty wide open than the 1.4G lens. At f/2.0 the differences are almost gone, that is you need some serious pixel-peeping to find any.
be a little bit more field curvature on the 1.8G but that can only be tested on flat targets.
comparable between both lenses with the 1.4G perhaps
a little more nervous in front of the focal plane. But again that is something that I'll have to specifically test for.
Transmission didn't show any obvious differences, but there is a real 2/3 stop advantage of the 1.4G and also the oof-blur is clearly stronger at f/1.4 than at f/1.8.
Here are both lenses wide open (f/1.8G 1st, f/1.4G 2nd), focus is on the center. Click through to large originals:
Nikon AF-S 50mm f/1.8G at f/1.8, 1/500, ISO 200
Nikon AF-S 50mm f/1.4G at f/1.4, 1/1000, ISO 200
So that's it for today. Please understand that these are preliminary findings from just one series of shots. I'll be off for Whitsun but will be reporting back as soon as I have more results.