I think that play alone give advantage if you know very well setting / map. otherwise it is irrelevant.

i don't know about szew/gnuff level, but at my level jsa and i catch eachother's mistakes

well, he catches my mistakes and i catch his mistake one time (jk)

point being a teammate can help predict strategies :P

I made a tournament to compare multiaccount teams to traditional teams. It is an 8 team round robin with strategic settings. Hopefully, I can get 4 teams of each kind, and we can see how it plays out. Let me know if you want to be invited and you aren't already.

if you know the template well, you have a big advantage. otherwise they would have never done that.