The PDC test device could be used inside a doofer to setup a a compensating PDC that is required by usage of fx that introduces a delay.
The device would require a “report only” mode for this, so introducing no delay itself.
For example: The haas panner doofer uses the multi tap delay device at 100% wet to setup delay based panning. Since the minimum value in the multi tap delay is 1ms, this is the introduced minimum delay of the doofer. Would be neat if you now could add the PDC test device with 1ms and “report only”, so renoise automatically compensates now using PDC.