I have one...she's eight months. I love the name, obviously.
I'm not one of those who hates it when other people want to use a name. I love hearing of other Marianne fans. We haven't met any other tiny ones yet so I think it's pretty unusual but, as someone else said, it's not kooky or out there.
Definitely not tarty, imo either! To me, it's fresh and a bit edgy whilst also being pretty. Hope that makes sense...