The filenames should be fairly self-explanatory with sRGB, Adobe and Pro referring to the three colourspaces used. They were all edited in their associated colour spaces and subsequently converted to sRGB and then 8-bit for JPG export.
UNEDITED - the original file converted from Lightroom without any adjustments. Nik - was using Color Efex Pro 4 with the Classical Soft Focus option DXOBW - was using DXO Film Pack and the Pan F Plus 50 film option DXOC - was using DXO FIlm Pack and the LoFi option Portraiture - was using Imagenomic Portraiture on a preset I made (in ProPhoto RGB but applied to the other spaces)
As you can see they all look pretty much the same with the exception of ProPhoto when used with Nik which is quite different. The portrature ones suffer from a slight difference in softening areas although this may be to do with the colour spaces effecting the masks for the skin softening.
I'm going to try running the same Nik filter through Lightroom 4 later this morning to see if there's any change there as well.
Interestingly when you edit an image directly inside Lightroom the 'copy' which gets processed on seems to be in a different colour space (I'm guessing sRGB), I can tell this as the yellow/orange glow behind Miss Pixie's shoulder on the left of the image doesn't blend as smooth in the copy compared to the original (which is what seems to happen when I edit in sRGB rather than ProPhoto, which I believe is Lightroom's native colourspace)
For anyone who didn't download the ZIP above, this is the image being used for the illustration (albeit this is my final edited one):