I think that sound and vision is recommending/musing about a wording change, rather than a new relationship type?
But since the discussion has gone that way - I don’t have much experience with either, but for what its worth with adding a new one I would be cautious about adding complexity/specificity if there’s a chance that users don’t know what they have. Then you would need two new relationships - ‘Continuous Mix’ + a type for people that don’t know if they’re dealing with a continuous mix or a DJ-Mix, that covers both. Brain hurt.