A very thorny subject !!
I always wonder , with no offence meant, why people shy away from using the composer tag for what it is !
Here's what I do ....
I set up Custom tags
Box Set
Disc Name
Disc Volume (eg Beethoven Edition has 20 volumes)
The Box Set is defined as a semi colon delimited collection of strings , so any CD can be a member of one or many box sets
The Disc Name can show many things depending on the Box Set in question, but mainly the individual context of the disc.
If we take the 104 CD set of Brendel , this is really a collection of "Box Sets" with a few solo cd's thrown in. So each CD has effectively 2 Box Set tags eg Complete Phillip .. ; Beethoven Piano Sonatas Analogue.
Similarly if you look at the big Yo Yo Ma or Glenn Gould boxes they are simply collections of single albums. So by appropriate naming of the Album Name and Disc Name you can organise a view that shows the glory of the original album covers , quite neat really. See the pic.
I use the Orchestra, Conductor, Composer tags as defined
If you now set up a view where Box Set is Not Empty , you will see some discs appear in 2 box sets . So you can have one set of files and show them in multiple ways. When you goto the Disc Name level it shows the "contents" of the Box Set as individual pseudo discs.
Equally the same CD's in the box set were originally an Album Box Set and can be named accordingly.
One of my Composer View goes Composer> Artists> Album . So in this example Beethoven Piano Sonatas will show as an album as well. You can even attach the original art work to the tags so yor Complete set will show the artwork of the orginal box Sets
You can slice and dice it as you wish .
I think the two takes are
- Don't fight shy of Custom Tags that's what they are there for
Use the tags as close to definition as possible (eg why put Composer in the Artist tag like a lot of folk do )
Standardisation is key , and you example of Composers hold true. Have a look at a demo of Musichi Tagger. It allows you to Clean the Composer , work and Genre etc against a set of standards (all for 20 Euro should you like it). I am not keen on the rest of the suite but the tagger is a gem and it will populate even Custom Tags from MC as long as they are they to fill...
good luck
Mike