I use *.mpl library export/import between different PCs fairly often when making File name changes in order to Keep the Date Imported Field intact and play counts.
I wish MC would try to relocate missing files that now have a different filename during import when tags are very similar with renamed files but I realise it might not be an easy task...(FileIngester is a good option for this but I prefer export/import of mpl..)
For example I renamed a bunch of lossy m4a to mp4 on one PC with MC27 and exported an MPL playlist. (This allows MC to differentiate bwn lossless and lossy m4a on handheld syncs but that's another topic
...)
When importing on a different PC with MC27 it didn't take some or most of the Playback fields such as "date imported" along with Play counts and maybe some others.
Importing on that same PC with MC26 worked flawlessly and got my original date imported back so something is broken in MC27.0.21