So the word back from Victor is that this flag won’t help with fout. He suggests it might not be that useful here at all, as it may also cause some init-passes to be held back until they are ready to be called, which may result in some timing issues. He also say that writing to disk with fout will inevitably lead to dropouts at some stage.
Can’t the DAW be used to record the output? Or, can you write the audio to function tables, and only bounce to disk at the end of the operation, so when a user hits stop, write to disk?