As a weapon, the Super Shorty is not suited for anything beyond close-range engagements. Rather, it's better suited for destructive purposes such as opening up hatches or quickly making lines of sight. The shotgun also provides the same speed boost as a handgun when equipped.
The Super Shorty's model is based on the Remington 870 Modular Combat Shotgun (MCS) (specifically the compact "Masterkey" variant), a variant of the M870 that is mounted with a Cadex Defence removable stock butt adapter, rather than the actual Serbu Super-Shorty.
The in-game shotgun's capacity of 2+1 is correct for an actual Super Shorty, however, the real-life 870 MCS Masterkey has a capacity of 3+1 instead.