Considering Rainbow Dash is both my least favourite mane six member and my least favourite pony, it would be.. Well, it'd be awful. Her ego is irrefutably superfluous and it'd drive me insane to hear her brag nonstop. Not to mention that even in a cartoon she can leave me seething by her insensitivity.
Basically, if that ever happened, I'm kicking her out straight away. She can sleep on a cloud. She does it often enough as it is.