"the choice of performers that are really able to intermingle all of these elements" seems like a large part of this gambit to me also.
Bill Dixon related to me a story of workshopping a piece with the Jazz Composers' Orchestra (I think this is also in Dixonia), where all these top JCO players were unable to get through the material correctly but Bill's right-hand saxophonist, Stephen Horenstein, who was then an unknown in NYC creative music circles, was able to navigate the charts and play his solos with the integrity and purity that the music required.
Bill also related to me that he felt his early work relied too much on written notes and very didactic situations, and it wasn't until he wrote less and let the musicians do what they did, that he felt his pieces did exactly what he wanted. That said, hearing Metamorphoses 1962-1966 and the pieces for the Orchestra of the University of the Streets (the latter were partly graphically scored), there's a very healthy and flexible conversation going on within arched structures.