I've never really found Rosetta Grunts that smart...I've sniped them with sniper rifle at close enough range for them to hear me even with a silencer and they just watch ther comrads fall around them, the only ones that seem to have any brains are the elites and the ones with the grenade launchers. The researchers tend to be the spray and pray types hoping thier drones can heal their asses.

They really aren't! Sometimes they'd go "Did you hear that?" while you're right in front of em or snipe someone and the person right next to them just doesn't even notice their coworker is dead xD