[Oz Cello]

For the advanced formatting I ended up using the composer field for classical music only and for non-classical music I put the performer or composer in the artist field. For hymns I put neither. I then set up formatting which shows composer and title if there's an entry in the composer field, but shows title and artist if there's nothing in the composer field. For hymns I don't enter a composer nor an artist usually. Took a bit of data entry to move the composer field to the artist field for non-classical pieces but it seems to give the results I was after.
%COMPOSER:${VALUE} ${TITLE}|${TITLE}    (${ARTISTS})% is what I've got for the title format. At some point I might set up a conditional for the ARTISTS bit so that it doesn't show empty brackets when there is no artist entry but it's all good for now. Awesome software.