The short recoil operated 1919 and 1917 machine guns are heavier, slower rate of fire, and take longer to conduct a barrel change.
That being said, machine gun math says that the gun that can put effects on the beaten zone longer is the better gun from a tactical standpoint. It isn't how much lead you can put on target, it is how long you can put lead on target.
That is why American GI's are constantly being harped on to conduct good burst control and conserve ammo.
Remember, it is never one single weapon system that wins a war, it is a proper mix of systems and combined with proper tactics to use those systems.
Machine guns are awesome until you have to carry one.