True Erax. I can't disagree with that one bit. The players working together will be at an advantage. Probably not quite as big of an advantage, but still an advantage. But if the allies are not allowed to declare themselves co-winners, you can use that possibility of breaking the alliance early against them as a wedge to try and break up the alliance. It's the classic weapon that small empires can use to survive in a game with larger empires. One of my favorite ways to play actually. My empire stays small so less MM, but I get to feel like I am still a factor in the game and manipulating the other players.
Of course you can't always do it succesfully. It's a skill that takes practice and talent, just like straight up empire building does. But with co-winners it's not even an option. Give me the option of at least trying it and I can deal with being a small empire among big guys. If I only wanted to be the biggest I would make alliances and trade tech.
Geoschmo