I'm not really sure which, of the two, they would want back for a future All Stars if such a thing were to transpire (I don't even know if they would just jump to the American edition, or create a British All Stars... it doesn't bear thinking about really
). If American, Vivienne would be more polished and ready to compete I think.
Just wish people weren't so wrapped up in "the nicest one has to win!" editing. Because it's clearly a level playing field between the two, and Vivienne's been funnier and stood out in challenges more