Use the peacekeeper over the MTAR for the same reason you would use the PDW or MSMC over the MTAR; mobility. Otherwise, the MTAR outclasses all of those guns. --- Soul Silver FC - 4469 3620 2054 / Diamond FC - 1033 3883 0634
I say Peacekeeper is better. MTAR has better range and does slightly more damage. But Peacekeeper is a SMG/AR combination. You can run around corners and spray the enemy before they knew what hit them and then ADS to take out his buddies down the stretch.