Upload & Sell: Off
Okay, let's look at lossless vs lossy NEFs first, which mainly affects the highlight regions of an image. I often hear people say that 14-bit images are better at recovering highlight detail, and give smoother tonal gradations in otherwise featureless expanses, such as clear skies.
Here are a bunch of sample images, all shot with the D800, converted to lossless DNG, then processed in ACR 7.0. Aside from the stated adjustments, I will rotate and align candidate images for easier A/B comparisons, and I will get rid of a couple of sensor dust spots.
100% crops can be downloaded here:
This building was shot 2 stops overexposed, then brought back down 2 stops. Before and after:
For those concerned with flesh tones, here are shots of my hand in sunlight, again shot 2 stops overexposed and then corrected in ACR. Before and after:
This is an early morning shot out my window, looking to the east. The colours are pretty drab, so I pumped it up with Contrast +100 and Vibrance +100. The second ZIP file above contains 100% crops of three strips across the image so you can examine the colour gradients. Notice any differences between each pair?
So far, not much difference at all between lossy and lossless NEFs. The only time I've noticed an advantage to shooting lossless NEFs is with pure blue sky, and again only as you start pushing the sliders really hard. Here is another view out my window, later in the afternoon:
I cranked up the Contrast and Vibrance both to +100 again. You can see some faint banding in the sky of the second (lossy) image:
Here's another example, late morning with the sun hiding behind an apartment building:
Contrast and Vibrance set to +100:
Note that if are shooting under different conditions or in a different location or time of year, you may get results SOOC that match my artificially saturated photos. In that case, a lossy NEF should be fine too, because the sensor is capturing those colours natively. Lossless NEFs make a difference if you start off with an undesirable capture and then really stretch what little colour you have. But if the sky already has that deep blue colour in real life, lossy vs lossless won't make a difference.