I've been listening to this argument since I got my carbine in 1991. In my view the military erred in allowing the carbine to be issued to so many troops in lieu of the rifle. The troops loved it and many of them were M2s - who doesn't like a small, lightweight machine gun? The problem was, it was never intended to be the principle rifle in an infantry unit - it was forced into that role. So any comparison of the carbine and rifle in combat effectiveness is moot because over-proliferation of the carbine was a strategic error on the part of the military. That means there should be no comparison because the M1 Rifle should have been the predominant individual arm. I'm sure it escaped nobody's attention that the Korean War marked the beginning of the end for the M1 Carbine. For that matter, for the full-power .30 caliber rifle as well, although the M14development was brought to it's conclusion and that rifle was used for a short time before the M16 took the stage - and that's another story, now isn't it?
The oft-repeated sentiment that the .30 Carbine round is a pistol cartridge is also incorrect. The round was developed by Winchester and was based on an earlier carbine round, the .32 Winchester, but with better modern propellant and jacketed bullet. The Army wanted a 'light rifle' for certain soldiers who normally would have only had a pistol, and the M1 Carbine did that job perfectly. Comparing it to the full-power battle rifle is simply pointless.