Has anyone done this? I would think they would be pretty comfortable and look cool...

I thought the whole point of promenade or northroad type bars was the comfortable upright riding position? If you want a shallow/wider dropped bar they make that, it's called a "dirt drop".

I love my upside down North road bars, I feel they still provide a good more upright position (than drops which are my normal bars) as they sweep back, I can imagine some promenade bars to be okay while riding but the ones with sharper angles I feel would give me wrist discomfort