Comparing azimuthing thrusters and conventional shaftlines for propulsive efficiency of pushboatbarge convoys

Azimuthing thrusters can serve as an interesting alternative to conventional shaftlines. But how does this affect powering performance and efficiency?
Pushboat-barge convoys offer great flexibility for inland cargo transport, being able to transport cargo on extremely shallow rivers. However, the meandering nature of rivers requires the convoys to have optimal manoeuvrability performance. Therefore, azimuthing stern drive thrusters (ASD) can provide an interesting propulsion alternative.