Hi,
I would expand scope.
Any filesystem manipulation on slave shouldbe done through transaction.
Right now delete file, delete directory, rename file/directory, delete replica done without transaction. All this should go thought transaction, and use file update mechanism to confirm transaction.
I think file /dir copy should go though transaction too. Or have separate queue for them, aside from replication queue. Entry from replication queue can be thrown away on some conditions, and operation will quetly die.
Thank you
Sergey