It's not a competitive advantage unless it's something you have and your competitors don't. Boeing has been selling 787s to not only UA, but also UA's competitors, so I don't think the 787 is a competitive advantage. And I don't think people would want to fly UA for this particular plane, if the service is poor compared to, say, an ANA 787 (except for elites, who might do it for the E+ seats, if UA installs those seats on that airplane).