If your an experienced player with considerable patience and the ability to creep through bush effectively then I say absolutely any airsoft weapon of good quality is sufficient.
A good quality pistol with heavy weight ammo will fire a good distance with fairly good accuracy.
A wise man once said, upgrade the player not the weapon. Thus if you practice and take your time with it, you can be effective with anything. I have in my time fielded everything from spring pistols, gbb pistols, m11, spring shotguns, to stock tm aegs and heavily upgraded aeg's. and frankly I was perfectly capable of getting enjoyment and playing "effectively".
Thus said, don't expect to bunker down with one, your going to need to remain mobile and unseen, which will depend on the chosen field and your abilities.