Hello,
I am a recent PM user, first post here.
Concerning Exiftool, the "experimental" version of XnView, XnViewMP (yes, MP
) has a nice and useful feature: in the Info panel that opens with each image, besides the Properties, Exif, IPTC, Categories, there is an Exiftool tab. One clic and you get the full listing of what Exiftool extracts from your image.
It is a lot. With a NEF, as Hayo stated, you get the Focus distance plus the Circle of confusion, the Depth of field, the Angle of view, etc. All this is interesting when analyzing an image and trying to understand why the main subject is out of focus.... Of course it depends on the MakerNotes, in Panasonic's RW2 there is less information. Nevertheless...
Could something similar be built in PM? with an entry in Preferences to indicate where Exiftool.exe is located on your drive, you can easily always have the most uptodate version of the program (8.54 at this time I guess).
Even better would be an ability to built custom variables with Exiftool tags.
Francis