I have the B&Ms,
- a short stem on the streetmachine.
- a long stem on the Furai.
Once you've got the angle right, they're perfect. The little ball heads do tend to wear a bit, but on mine this has resulted in a set of indexed positions. Typically I have the 'what's behind me or just off to my right and behind' position as standard, one bump with the cuff will put it into 'is that guy riding gutter-side on my wheel keeping up', a knock on the top will give me the 'is my back tyre down?' view.
The fourth configuration is the 'hey, you took this through a doorway again didn't you' position. That's not so good.
On USS two wheelers, the most tempting place is to stick them below the grips, sticking out. It adds about 3 inches to the bike's width, and invariably is the first piece to contact when you lean her against a wall.