I've heard stories and have read reports from WWII combat vets that preferred the M1 carbine to the M1 Garand, for probably the same reasons Mr Rogers loves the M4 so much. It's light and handy, and given the infantry tactics our military uses these days, it works well enough.
I've heard stories and have read reports from WWII combat vets that said the M1 Carbine was inadequate, and that they preferred the M1 Garand. Similarly, I've had guys from Vietnam say the 7.62mm weapon was a better stopper than the 5.56mm weapon. Now, granted none of these guys teach classes at Gunsite, but I don't think anyone I've spoken to is a liar.
I certainly don't think Mr. Rogers is a liar.
So who do you believe? One guy who's BTDT tells you one thing, another guy who's BTDT tells you another. Both are only going off of their experiences, and what they've witnessed. No one's done a scientific study of any sort in this area, so all we're going off of is the observations of people who've used these weapons in action. It's about as un-scientific as it can get, so looking for absolutes is futile.
No one weapon is good for everything.
Personally, FOR ME, the best balance comes in a 7.62x51mm semiauto with a 20 round magazine. You can get rail handguards for the FAL if you're inclined to hang all the stuff off it (I'm not), and DSA sells 16" lightweight carbines that are probably only a little heavier than an M4 (much bigger fireball, though).
But then, I'm not worried about a SHTF scenario. If I were, I'd prefer a weapon that could defeat cover, and a 21" .308 has a big advantage over a 14.5" .223 in that area.
It depends on the mission, basically. I read, in SWAT Magazine, in an article by Pat Rogers, that the Marines in Iraq are complaining that the M16A4 is too long for the mission (he also ponders why the Marines didn't adopt the M4 wholesale).
On the other hand, I saw combat photos from Afghanistan, featuring the Marines, in SOF Magazine, and that's some WIDE OPEN COUNTRY. I think the 20" would be better there, given the longer sightlines. Also, in Afghanistan, the combat involves riding in a vehicle or crawling through small houses less often.
So, in one combat envionment a short, handy weapon is perferable, but in another, the one with longer effective range is better.
Unfortunately, there's no free lunch. You can't have a 30" long, handy dandy carbine with a 22" barrel to maximize ballistic effectiveness. You can carry 2000 rounds of ammo, but not if it's bigger than .22LR, and .22LR doesn't make much of a combat round. It's all about compromise and what you're most comfortable with.
So basically, here's what you do. Determine your mission requirements, then pick the weapon. People are trying to do it backwards, I think.
Now, right now, a 21" DSA FAL is the only rifle I own. It's not ideal for some situations, but is ideal for others.
Regardless, I don't think Pat Rogers, an advocate of the M4 carbine, nor Jeff Cooper, an advocate of the M14, nor John Farnam, yet another advocate of the M14, would tell me to get rid of my rifle and buy something else, if I'm good with the rifle I've got and it suits my needs.
Personally, I don't care what the military, the Navy SEALs, the Police, the Israelis, or anybody else uses/carries. Marines in Iraq have different needs in a rifle than I do. The Police have different needs in a sidearm than I do.
Sorry that got so long, but really, all this "which is best" stuff, quoting this or that instructor/Guru/veteran, is an entertaining but ultimately futile mental exercise. (Makes for fun debate though!)
But getting back to the original question, it's about the compromises you're willing to make. .308 is the the power-to-mass ratio that I feel best with. However, 444 and Mr. Rogers obviously prefer the less power, but less mass quotient of the .223 cartridge (less weight means more ammo).
But, before you decide how powerful your ammo needs to be, or how much ammo you might need to carry, you'll need to determine what your mission requirements are and go from there.
