It would be great if you guys would implement an award system for missions. When a player finishes a mission, he/she gets an award and another, more difficult mission, unlocks.
Something like this:
[img]http://img197.imageshack.us/img197/3881/dfspt.png[/img]
Also adding a new mission in every new MG version would encourage players to play the game and train themselves to become more skilled.
PS: The gained score for completed missions could be uploaded to the Masterserver, so every player (nick) would have it's custom stats. So everyone in a game lobby would know how skilled is each player, which may help to set teams to be more balanced.
I know, that the stats might be faked etc., but I think that the most of the players are honest and would not cheat. Otherwise, it would not be such fun for them to play,