I personally think that the best long term solution to each person getting what they want from an artist field for releases, RGs, etc, is to get rid of the "artist" field, in favor of ARs. The artist created by the new classical/release/artist "Mozart, Britten, Tchaikovsky; The Norwegian Chamber Orchestra, Iona Brown" is not a useful artist for the person who, for example, wants to tag that release. Add in the RFC'd change to make performer the artist for classical recordings, and the likely future RFC to do either of these to track artists as well, and MB becomes essentially useless for tagging any of the composer-as-artist genres in any useful way.

At the Release or RG level, there is no work-equivalent which would allow for composer (or conductor, or performer, or whatever else you want) to be selected. Right now, it's just a meaningless blob of names and groups. Using ARs, ala works, instead of artists, seems the solution. But how to get from here to there without just assuming the role of every artist (as with the recent types migration) and likely getting many of those assumed ARs wrong?

I suggest doing it the Amazon way as an interim step. Add an AR dropdown next to the artist fields - (artist) (AR) (joiner) - and make it a manditory field. Over time, more and more release-artist ARs will be created, and those new and existing release/RG-level artists will begin to have roles associated with them, giving a reason-for-being-there to each name again. At some point, hopefully, then there is sufficient critical mass that a transition to ARs (and dropping of the "artist" field) could be done with far less of the db's release and RG artists having to have their ARs guessed.

Example: http://www.amazon.com/Britten-Persons-Orchestra-Variations-Symphony/dp/B0000041S6/ref=sr_1_2?ie=UTF8&qid=1337135839&sr=8-2
Benjamin Britten (Composer), Benjamin Britten (Conductor), English Chamber Orchestra (Orchestra), London Symphony Orchestra (Orchestra)

Side note: Since this would change the meaning of release-level ARs, http://wiki.musicbrainz.org/Style/Relationships#Crediting_an_artist.27s_role_at_the_track_vs._the_release_level would need to be modified/updated.