I don't think 4 players per team on Siege will be a sufficiant amount.
4 players is only the minimum. since the server will only be able to hold 16 players, we figured thats a reasonable minimum.
as long as both teams have enough guys and agree, 8v8 is possible. its just that you cant ladder with less than 4 players unless you want to play shorthanded.
i appologize for the forums not being up yet. the forum team hasnt responded to my request yet