Rob,
I'm going to be brave and take a crack at it.
I do have another quick question though.
When there are "multiple sources" for data (for example, as presently configured I find Metering Mode under [Shooting Info] also under [ExifIFD] and there's probably a [Nikon] version in there too), I presume the trade-off is that the more specific (i.e. Nikon data) might be more accurate or detailed, but the more general (Exif data) would display data for a broader range of pics (i.e. for images taken by non-Nikon cameras).
Is that about right, generally speaking?
Any other quick rules of thumb like the difference between data sourced from:
Composite_
ExifIFD_
Adobe_
Nikon_
XMPexif_
etc.
PS - I love the "Hide Boring Tags"...all software should have a "hide boring" button!