Well, your omniscient narrators become characters, and wonderfully and bneautifully so, and I love that about your fics. But I'm not sure that it necessarily happens in any meaningful way--yes, the narrator in a Tom Clancy novel is imposing order/bias, but the mock-objectivity doesn't really draw attention to itself.

And I think that's really what is at stake at here--River's presence means I can't head-jump in the middle of a scene without drawing attention to the shift the way I would if I suddenly switched from being in Kaylee's head to being in Inara's. It's not really a question of constructing a coherent overall voice, although in another fic I could totally do that and it'd be cool.