Last detail has to do with how the cables cross above the stem extension. I usually find that if they are crossed one way, that the housings touch and remain in contact.
But putting the other cable in front may leave the two housings separated by some distance, often with one of them clattering against the handlebar or stem.
My preferred way here is to have the cable housings touching, and with the front brake housing in front of the rear brake housing where they cross before going to each side of the stem.
This is for non-aero cable routing of course.