SHOOTALL, there is a place for virtually every weapon ever divised by man, in todays, and yesterdays combat zone. The Afganies found that shooting a pure lead ball out of a muzzle loading rifle at the tail rotor of the elite Soviet Union assault helicopter many times resulted in the soft lead ball sticking to the tail roto like a mud ball might, throwing the tail rotor out of balance, and causing the helicopter to go down.
Yes, much experimentation has taken place over the years, for SPECIAL circumstances in war. I believe thru my extensive training, and use over a 20 year L.E. career of the M4 and it's predecessors, such as the CAR15, along with men such as my son's own testimony whom have FAR MORE trigger time in ACTUAL COMBAT CONDITIONS than I ever had, that the M4 is a GOOD COMPROMISE of a do it all weapon for the combat soldier. Is it perfect? Of course not, but I had rather carry 200 rounds of 223 in 30 round magazines, than 60 rounds of 308 in 20 round magazines, with little difference in weight.
War by yesterdays standards is very mobile. The enemy is harder to identify, and we have gone from trenches, to house to house. Speed and fast handling is truly of the essence. The recoil is very light causing recovery for follow up shots to result in a much quicker succession. Ballistic data matters very little if one gets a solid hit on an opponent.
The bottom line on every post on this thread is we are expressing our own OPINION of the weapon, based either on reading material, someone else's testimony, or by personal experience with the weapon. None of which is to say one is more right than the other. I have a totally opposite experience with the weapon than the media is portraying but with that said, I trust very little the media says anyway, whether it be CNN, FOX, or whom ever. I consider all to be entertainment with a little truth thrown in. One must merely pick out the style and view point the one wants to see and hear and pick a new media source according to one's taste.