By the way, the reason I would use the importer plug-in as opposed to jjust importing into lightroom is that I would lose the image enhancements as well as all the cataloging by album that I hope to preserve.
I would not call this plug-in a supported way to migrate, because the support is poor and it is nt a full migration - perhaps that is where the misunderstanding is coming from. The plug-in does only part of the job. The list of what it cannot migrate losslessly is long, none of the adjustments. Even when using the plug-in you will have to recreate all your edits again in Lightroom.
As to the IPCT and EXIF, the keywords - the plug-in does only transfer the fields that would be transferred anyway when exporting the edited versions. What it makes it easier is preserving your library structure as close as possible.
I would not migrate this way. Since I have to edit every photo again anyway, and the smart albums cannot be mapped exactly to Lightrooms structure, I would use the chance to rethink the design of my library and start over by making a clean, new design and weeding out redundant photos.
Just like throwing out most of the garbage, when moving to a new home.