I think the slower cyclic rate of the M2 .50 caliber is sexy. I think the MG42 is demonic. I think the M61 Vulcan is a look at hell.
And the M242 Chaingun (the real Bushmaster 25mm) makes the Ma Deuce look like a dehydrated .22
Standard version 1, 100, and 200 RPM, beef up the motor to 5 HP and yuo double that rate. Incredibly powerfull and with all the gee whiz bang 'lectronic sight and ranging aids deadly accurate at ranges that are mind numbing. Put in a box of AP DU rounds and nothing rolling within sight is safe... Imagine sitting on top of a Bradley in an indoor range (Pictinny Arsenal) up on the turret doing 100 RPMs. Ever see a dog hanging it's head outside a car window at sixty??
And yes, the M2s rate of fire is awesome, but then again so was the M60, when it was properly headspaced, which was seldom due to the rotating locking method used. If I had a dime for every barrel and bolt I replaced. I was as happy as said hound dog when the M240B came out. I was madder than a hornet when the US bowed to NATO pressure and went to the M9, luckily SOCOM kept the 1911 option open, which is still in use today by todays finest, albeit in the form of a Kimber of NM version, but still dropping bad guys over 100 years after it's intro to the world... And then we have the M3A1 Grease gun (M3 had a failure prone charging lever, A1 variant just cut a large opening on the outside front portion of the bolt). The M3 took an artist to fire effectively as it had a climbing rate of fire, being as it fired from the open bolt position (massive bolt) the first shot invariably went low, second shot high, and with much control the rounds eventually found there way to the target. I think it was designed for tankers to convince them to keep their tanks on the tracks and in good working order. I'll save older machine guns and mortars for later, but in closing, canning the 4.2 was akin to replacing the M60.