It seems your knowledge of typography is lacking. Vertical signs should always be in caps due to even row height of capital characters. Lower case letters range from x-height to cap height. Not to mention the descender space. All of those things in the end make vertical spacing uneven and therefore mostly illegible. Caps on the other hand offer that even spacing which is required for vertical signs. I for one would restrain from vertical signs if at all possible. Since bauhaus was known for its use of lower case lettering I would use a rotated lower cased sign in a heartbeat. Being only one word and gaining consistency with this action it would be entirely justifiable from my point of view.