I agree with WarchrisMA about the importance of the size of the map (and more especially about the total number of countries on the map).

For a low number of countries, red has clearly a very big advantage while this advantage tends to lower more and more as the number of countries increase. This become clear when you look what is the situation for both

minimum number of countries (i.e. : 4) and maximum number (i.e. : an infinity) (I speak of the theoretical limits, not the practical one

) ).

For the lower limit (i.e. 4 countries), as each player must reveal 2 allies in the begining, all the countries are revealed in the first turn and so each player know exactly where are the position of all the ennemies countries. In this situation, playing the first (i.e. playing PL) is decisive and so, for opponents of similar skill, it will almost always be the red player who'll win as he'll strike first.

For the higher limit (i.e. an infinity), this has no impact at all because 2 countries is nothing compared to an infinity

Personnally, that's why I prefer playing big maps (at least when I play green

)