While making a comment on a post concerning authenticity over at Gretchen's Pianos, I thought of the attitude certain kinds of performing musicians have towards an audience is that of a kind of "movable me." Very often this kind of performing musician's playing involves a kind of schtick, and often this kind of performer considers the audience something he or she is playing "at" rather than "to." This is not always the case, of course, but it is often the case when a performing musician considers a performance "all about me," rather than "all about the music."
I'm coining the phenomenon of a touring musician, who has very little regard for either the audience or the music he or she is playing, as a case of "movable mi."
I suppose you could have movable sol for a truly heartfelt performance, where the traveling performer shares very deep personal feelings and insights through his or her music making to every audience (this would be the opposite of "musical mi"). Movable re would be appropriate for a touring musician who brings lights, electronics, and other technical glitz to his or her performance venues. Movable ti could be appropriate for harpists and small ensembles who play at teatime in fancy hotels (movable si would be for entertainers on board ships). We shouldn't forget the other kind of movable do. That's what you get when a performing musician is paid by a third party.