Originally Posted by flyerdude88

Definitely the way to go. I just matched over from UA and my account hadn't updated on my IAD - LAX and LAX - IAD flights last week and in both instances MCE was wide open and no seats were open in non-MCE Y. I actually almost bought MCE for the LAX - IAD return (it was a redeye so it seemed worth it) but when I checked in I was assigned an MCE seat both times so there is definitely a good chance you'll end up with an MCE seat after all