So after a short investigation it seems that:
If we forget about the number of passes, generally the DR works fine, because the same image is rendered faster.
The issue here is only that the same noise limit requires different number of passes for local rendering and for DR.
The explanation is that the nodes will keep rendering until they receive a "stop" command from the workstation, and they are sending the rendered output to the master based on the "synchronization interval" (60 seconds by default) in Render Setup > System > DR. So it may happen that the nodes will send their passes to the workstation, but the noise level will not be reached yet, so they will keep rendering for 60 more seconds (or other time specified there), and then send their passes to the master again. This may result in slight "overkill" in the number of passes, but that's expected.
Here are some measurements by Hrvojezg00:
Full render:
DR: 10:17 min, 727 passes
1 WS only: 36:27 min, 445 passes
Crop:
DR: 4:20 min, 715 passes
1 WS only: 12:28 min, 470 passes
If anyone observed something that would negate our explanations, please let us know.
We are also interested in any other DR-related issues.