Why not base it on the full Arma 2?
The question is totaly appropriate and was the result of a lenghty discussion which I can summarize as :
``Not knowing what will be the response of the community and the interest brought by the Mil-sim genre, we can conclude our best bet for the time being is to allow a maximum of players to join in. This will allow us to test both the response and the preferences from the players. Once this step has passed, we will be in ability to take a decision on future servers.`` In other words: F2P will be the first server. If we see it generates interest and players bring in ideas, we will think about an ArmA2:OA server or a DayZ server or whatever will be possible/in demand. So it is not that we don't want to but before investing alot of money into a project, we would like to see if there is a market for it. If players tell us : WAIT FOR ARMA 3 ZOMG

, we will wait for ArmA3. If people say ArmA3 require a too big machine and want OA, we will bring OA. If DayZ remain the most popular requet, we will bring in DayZ. The Mil-sim project is still early.