The SMG-11 is a fast firing but unstable weapon, as it's recoil is incredibly difficult to control. This means that while it thrives in close quarters, it struggles at long range without tap firing, not helped by the fact of its incredibly high fire rate.
The SMG-11 has a side-folding stock that is similar to the one on a Mini Uzi, instead of the telescopic stock used on a regular MAC-11.
The name SMG-11 is also used in Watch_Dogs, another game developed by Ubisoft.
The SMG-11 in reality fires in an open bolt configuration, meaning that one in the chamber would be impossible, unlike the in-game counterpart, which holds one in the chamber. This error is shared with other guns with an open-bolt configuration.
The SMG-11 has the characteristics of a normal MAC-11, but has the upper receiver of a Masterpiece Arms MPA10SST, chambered in .45 ACP like its larger cousin, the MAC-10, denoted by the shape of the injection port.
The model appears to be using the 32-round magazine of the MAC-11, even though it has a capacity of only 16 rounds. However, the SMG-12 utilizes it's 32-round capacity.