re passive mode)
This mode have only one advantage (for a some specific networks) - the node keeping itself synchronized with the UWB network and the only one advantage is that the firmware update feature is active in this state. So when the firmware gets propagated trough the network then the node in passive state gets updated too.
Re Responsive mode)
In the responsive mode the node does not go to sleep mode between TWR and it is synchronized with the network all the time. The advantage is that it always tries to select best anchors for TWR. The disadvantage is much higher power consumption. The opposite is low power when the node goes to sleep between TWR and it search for a new anchors only when the connection with the current anchor(s) is lost. The advantage is a much lower power consumption.