Without the Marksman DLC you won't be able to use some of the weapons on certain multiplayer missions (like King of The Hill). Some of them are better than the default weapons (Navid > zafir, etc.), so it really should have been included with the game by default. You can get by without it though.The heli and kart DLCs let you drive a few extra transport helis and the go karts respectively. They are not critical, just fun little extras.
6/18/15 at 1:25pm