It will be coming ... I think that 0.9.14 actually supports the following scenario:
1) add a directory
2) add new files to that dir
3) add the directory again
4) only the new files will be added to the playlist (comaprison based on name + size)

See if that works... Of course that random PSOH problem still floats around... not sure what to do about that one. I think it's a result of bad (non-existent) error handling at the protocol level.