What are the benefits of utilizing two 20A breakers versus two 15A breakers on a 30A PDU?

20A breakers in a 30A unit allow maximum flexibility of load connection without nuisance tripping. The receptacles in a 30A PDU are divided into two independent groups. A 30A PDU distributing to 15A or 20A receptacles must be broken down into either 15A or 20A circuits internally. By opting for 20A internal circuits, PDU circuit balance is less critical. One circuit may be loaded to greater than 15A. This would not be possible if each breaker were rated at 15A.