My stem is flipped down, it always has been, that's just how my bike was fit to me. But today i was trying the new trendy aero position from the TdF. (sitting with your boys on the top bar and shoulder on your handlebars) I was trying to put my shoulders onto my bars and couldn't do it because i was hitting my chest on my stem, i'm sure if it was flipped up i'd fit better.

Also worth noting, I think I figured out why they like this position so much. You don't have to crane your neck up so much in order to see while riding like that.