I'm far behind many of you, but I finally turned off DNIe using Eliab's instructions (reposted on post #7606
of this thread).
I am completely impressed with the results of this procedure. Two settings in particular have a significant effect upon picture quality: SNI_PROC_BWS, as has been mentioned by several others, and SNI_PROC_DEP.
The BWS setting has a huge effect upon shadow detail. When on, it really crushes lower shadow detail into black, resulting in an overprocessed and unnecessarily dark picture. I was shocked to see how much shadow detail was revealed when I toggled it OFF -- doing so put a big smile on my face. The BWS setting was definitely the culprit behind my nagging doubts about crushed blacks on my 5078.
The DEP setting, when ON, applies heavy edge enhancement. For those of you familiar with Adobe PhotoShop, it's analagous to the effects of using Unsharp Masking to increase edge contrast in a photo -- if you have a light grey circle on a dark grey background, the light grey pixels at the very outer edge of the circle are made lighter, and the dark grey pixels just outside of the circle are made darker. When properly used, the technique can increased the perceived sharpness of a soft image, since the edges appear to be better defined -- but when improperly used, it can easily create strong "halos" or double-borders that can be quite distracting.
Some here have liked the effects of the DEP setting, others have not. I'm a purist when it comes to things like this, so given the choice I'll turn choose the unaltered image. The benefits of having it OFF, for me at least, became more obvious when looking at contrast-heavy edges during movement, as opposed to a still image. To my eye, a good HD signal looks a hell of a lot smoother and more natural.
I'm still debating where I want to leave the GAMMA setting. I currently have it at 0, and chose that setting because at 2, colors appeared to have a slight amount of unnatural oversaturation. This was most noticeable in the greens on my set, but that bias might just be due to inaccurate color decoding or white balance that would need professional calibration to correct.
Just thought I'd share ...