If a record company only has the (matrix/discrete) LP and/or the Q8/cassette tape of a quad mix, I'd restore and use both (and include the matrix encoded stereo too) on a single optical disc of the album.
I would really like to just listen to the (decoded, if applicable) quad mix [restored master tape/restored LP/restored tape, my only QS and SQ decoders are in a ~50 year old QX-747], preferably on a Quadio style Blu-ray audio (DTS core + HD).
I bought the LaserLight needledrop CD back in 1990, it sounds OK, I thought it was quite a clever way to make a CD version of a direct cut disc, Sheffield Lab did this too with 3 of their albums (IMHO, they sound spectacular, although I can hear the noise unique to vinyl when I listen with headphones):
https://sheffieldlab.com/item.php?item_id=45
QS - no logic decode - if a quad mix was monitored through a QS encode/decode cycle before variomatrix decoders were available, then the mix was "optimized" for the limitations of a QS no logic decode and I would want that listening option.
Kirk Bayne