I found it interesting that ReiserFS was pointed at as having amongst the best handling of errors, passing them back sensibly to applications.

Also interesting was that they pointed at using SQLite as a way of mostly hiding applications from worrying about such troubles.

Also entertaining was the notion of "MBox considered harmful"; makes me like MH and Maildir all the better, as they have the merit of storing a message per file, so that there's fewer concurrency issues surrounding re-opening files and rewriting them. (Possibly I'm wrong, and the problem just shifts to directory metadata access...)

When confronted by a difficult problem, solve it by reducing it to the
question, "How would the Lone Ranger handle this?"