What we know of Maurus and Placid comes from the Dialogues of Saint Gregory the Great. More on their life may be found here, including a discussion on miracles and the blessing of Saint Maurus for the sick.
One of the strongest associations with Benedict, Maurus and Placid is their devotion to the Cross of Jesus as life-giving and life-saving.
Saint Maurus is credited in the Benedictine world with bringing the Rule of Benedict to France.
Saint Placid is credited with bringing the Rule of Benedict to Sicily.
What we gain by following the life of these two early companions of Saint Benedict is the resolve to follow the authority of another who is close to God, and to be familiar with God, as the Prophet Samuel was.
Here is a previous post on Saints Maurus and Placid.