All I can say is wow, On 160m tonight, I had noise that would not let me hear anything. I turned on WNB and it completely removed it. I also tried using the NB, it removed the noise as well, but did not clean up the panadaptor. That was so impressive.
It sounds like to me, for some, it would be best to make a noise reduction that simply blankets the whole receiver as it does in many other radios and not target types of noises at all. The WNB and NB is meant to be effective on one kind of noise, and it is amazing how great it works with that type of noise. I think they assumed that people who live in city's would have electrical line noise more common.
Here are my screen shots, the first one with WNB on.