The thing about a weapon choice that I dont see alot of here is what the weapon was designed to do. In the real world that means more than here in airsoft because the ammo is all the same (more or less
) and the shooting does not vary too much from weapon to weapon. In the world, you select your weapon based on its use. MP5 is a Ranger's choice for recon, CQB, and anything where you dont plan on getting into a prolonged firefight. Its quiet, small, and sweet on the trigger! (The real ammo is a factor here too) For prolonged patrols, large scale ops, and heavy fighting, the M4 would be the choice, partly on its better ability to law down supressive fire, and the 5.56 ammo is more of a battlefield ammo, and it works in the saw so the whole team carries the same rounds.
If I was deploying in the world, I would have an MP5, M4 carbine with a 203, Winchester Defender 12g shotgun (fits nicely in the side of your ranger pack), a Glock (.41) and probably a Mk23 with silencer..... that covers almost any battle condition I might expect. Of course someone has to man the SAW and the 60..... IMHO