WLPG metadata damage with people tagging confirmation?

[neebah]

So I know that using windows or WLPG to add descriptive tags has a tendency to damage the maker notes (because it writes to both an xmp location and the exif xpkeywords spot.  However no such exif location is altered with people tagging only exif.  It doesn't appear that any image data or metadata is destroyed using WLPG to add just people tags.  Can I get some confirmation on this.  I'm 99.9% confident but that with my eyes only.