Me too, Im afraid too look though, OB doesnt have the best transition from nifskope to ingame if you know what i mean, Im gnna wait till we finish with our radiosity, and see if that looks better.
Nifskope is opengl and the game is a directx renderer. All the render settings are basically close approximations made by the nifskope devs when they first build the renderer. So in other words- they are completely different! do not bother thinking anything will work in game until you test it. it'll be a mistake.
in the game itself, parts of the renderer can actually be removed from the engine altogether. < there are several features that I know of disabled. and several I have heard that are as well. :shrug:
in the gamebryo material, the detail map is supposed to be a an additional texture. Apparently, it is used on a different UV channel, a mask like texture is used in the slot. It modulates the base diffuse map. midgrey does nothing to the texture, lighter greys will brighten, and towards black will darken the base map.
The dark map is the same thing. but only works backwards from white. ie white does nothing, going darker from there will darken the base map. its supposedly used on things where there is static lighting, and creates a faux AO.
Bummer that the game disables the normal map when you use it tho. it shouldn't- but could be tied into that there are only 2 uv channels. 1 for the texures and 0 for vertex colors. ? something to think about maybe. I have heard multiple uv channels do not export with the niftools, and I have heard that multiple UV channels aren't supported in the engine- but have no verification, and I can't remember who actually said that, it might be worth taking it with a pinch of salt.
iirc, I have only seen 1 person use them in their models> you can use the civ4 plugin to export all this stuff- it is pretty much a version of the official gamebryo plugin, with tweaked export scripts that target the civ4 nif version. and includes a version of the gamebryo material.
edit:oh and bethesda has rewriten the shader code for F3. they use a homebrew one, and all of the detail, dark, and decal maps are not used any longer. So I wouldn't be surprised if those maps don't work right in Ob, as they had already made a crap load of in house changes to the engine by then.