The article was great other than the extremely fast and loose comment about 3.6.30 and writeback. From the linked article:
"Ted Ts'o has mitigated that problem somewhat, though, by adding in the same safeguards he put into ext4. In some situations (such as when a new file is renamed on top of an existing file), data will be forced out ahead of metadata."
Please clarify or contradict that before you give us poor app developers any more heart trouble... thanks.