I've tried to play a serious game of multiplayer on Civ V with around 6 teams.
And what usually ends up happening is the top two teams stay and everyone else quits.
That or there is that person who takes ~5 minutes on each turn holding up the game and then forcing everyone else to quit out of rage.
That being said, if someone wants to play me on Civ V in a serious game I would love too.
I have the Gods And Whatever expansion as well.