Hi Joe...its a personal thing really, but if you look at the stance of the CB400T, it has more of a cruiser look, the back is lower than the front and the front wheel is a inch bigger than the rear, so by switching the top yoke, allows you to let the forks come up more in the clamps, giving you a more neutral stance...the bike looks level in other works..I will post some pictures, when I have the wheels back on the bike.
Regards Eoin