Some personal suggestions about his project:
1) Content type: Artist -> Related Artists | Relationship
2) Content type: Releases -> Contributed Artists | Relationship
3) Content type: Releases -> Genre | Taxonomy term field
4) Content type: Bands | Should be of node type and be created by Relationships with the Artists.
A general 'best practice' here is this:
A taxonomy term is used to categorize content. A relationship is used to create a relationship between 2 or more content types. The taxonomy term will have a default path to display but the relationship won't.