You'd hope that someone buying an M3 would have driven all of the styles in which they're interested; and thereby, would know whether they want a vert.
The top is down on mine more than it's up, and it's great. One thing I'll say though, you have to be ready for the vert experience. My wife and I put the top down, she ties her hair back, and its windy, loud, and fantastic. When her friends got in the other day, with their hair perfect and makeup just so, they lasted with the top down about five minutes.
So I think you have to be ready to be out in the open, and enjoy it.
2009 E93 M3 - it's, um, pretty fun