One of us has. I've had three different karate sensei's, one Brazilian jujitsu instructor, an army ranger, and several marines tell me that you're better off watching the eyes. Also, in the tournament fights I've been in, watching the eyes has made me less likely to fall for a trick move.

Edit:
Don't get me wrong, I'm not trying to say I'm an expert, because I'm most definitely not. However, that's what I've been told by several people I would consider master martial artists, and it holds up in my limited personal experience.