I have a customer who tried to use matrix items when they first went live and who ever did the implementation didn't understand how Matrix items really worked so they abandonded creating new ones.  They now have approx 4000 SKU's that should really be child records under about 180 Parent records.  They are in the process of implementing Suite Commerce advanced and Matrix items would definitely make their life a lot less miserable.

I did a CSV import to update the records to point to a new parent record and added Matrix options.  The subitem of appears to work as the child records do show they have a parent but the Matrix Options do not appear anywhere and the parent record does not show it is has child records.