The main disadvantage is the increased likelihood that any given tf victim involved might not want to be transformed, but as long as it isn’t permanent and nobody is hurt, I think the impersonal/untargeted nature of the transformation and the “all in this together” dynamic are actually quite comforting! A bunch of transformees trying to figure out their new forms together… maybe helping each other out of their clothes, vehicles, etc… forming ways to communicate… very very comfy ngl. Overall I think I love mass tf!