A 1v1 I think makes asymmetries more apparent...the law of averages is going to make bigger maps with more players generally more "balanced" in terms of starting positions...
If you have a crap start in a 1v1 but your opponent doesn't, then you are at a huge disadvantage...but in a 5v5, the odds of all "Blue" team's starts being awful and all "Red" team's starts being great is pretty slim...
That being said, 1v1s and 2v2s tactically are always balanced because there can never be a difference in number of eco players or suicide spots between the two teams...smaller games also are less likely to lag or experience mini-dumps (which often can decide a game)...
Bottomline: while there are some exceptions, in general larger games are going to be more fair to each team (though not necessarily each individual)...
