Hi Chris:
The second set I posted are not screen shots, but jpeg conversions directly off the tiff, so are the best I can show you online...
That said, yes *ALL* NR tools reduce detail to some degree. In addition they "smear" color. The bigger issue here is how much color-channel smearing goes on beforehand during raw conversion. IMO with AA-filtered DSLR's it is a lot -- and thus the additional from the NR tool is usually not all that bothersome as it is only adding to what is already there. This smearing is what renders the waxy or plastic color effect many refer to when comparing a typical Nikon or Canon shot to a MF DB or M8/DMR non-AA capture.
When you use the NR tools on a non-AA sensor, the color smearing is fairly notable (and most of us don't like it) and IMO gives an appearance of even less detail -- probably not the case in reality, but it's what it looks like to me at least. However, *most* of the time, cleaning up the noise and getting the color smearing is preferable to not cleaning up the noise at all -- though I will go on record stating that any NR routine definitely detracts from overall file detail, so finding a happy medium on the amount applied is key.
The things I like about DFine are 1) it has a very intuitive UI, 2) it allows you to easily adjust the Luminance noise reduction (detail) separate from the color noise (smearing), and 3) it has an option to output the NR as a layer over the original in CS, very beneficial for further tweaking and masking. That said, I think Noise Ninja and NeatImage are also a very nice tools -- my recommendation is to download and compare the trial versions of all three to see which ultimately suits your workflow best.