This is all over a 480P DVD signal, so I haven't had a chance with DVD or Blu-ray over HDMI. There are about 30-40 hours on the TV at this point:
O.k., so I spent more time with the TV last night, and my gains and offsets above in post #49 still provide a very good greyscale.
However, I'm not too thrilled with how the Samsung handles color. All of the primary colors (red, green and blue) are oversaturated, and the saturation can't be fixed with the color control. The hue(tint) of red and blue is pretty good though, and green had a slight blue hue but not terrible. The tint setting only seems to affect the secondary colors to any significant degree, but you can't get all three secondary colors to line up properly. You either get yellow looking correct, and cyan and magenta will be off. Or you can get cyan and magenta correct, but yellow will have a red tint.
The problem with the color setting is that it's not adjusting the saturation of the colors, it's adjusting the brightness of the color. Getting technical, color is made up of three components. Saturation, Hue(tint), and brightness. The color setting should adjust saturation if it is working correctly, but on the Samsung it adjust brightness much more than it does saturation.
Does this mean that the picture will always look bad or incorrect? Not necessarily. To correct for oversaturation of a color you can reduce it's brightness. This fools the eye into thinking that the color is desaturated. The settings I posted above are the best comprimise I could come up with for color and tint. This will have everything looking o.k. except for cyan and magenta, which will have hue off a little. (probably not noticeable to a lot of folks)
If you want magenta and cyan to look correct, but have yellow with a red tinge, you can try this setting also:
In the advanced menu, turn colorspace to Native, and then set the main tint control to G26/R74.
Those are the two options, but keep the color setting around 40 to help tame the oversaturated colors in general.
EDIT I've included charts above with my measurement results to show what I've been describing.