Thanks for the reply. I played with it a little bit, and I think there could be some contention. If two users created kids for the same item, the kids entry in the 'item template has to be updated to reflect the two new articles (ie, the item has to be serialized again). If the users are on different instances I believe you could lose information ... I think :)
Also, it doesn't seem save-table is safe in the sense that it just overwrites the file that's already there (as opposed to writing it with a different name, and just 'mv' over which is supposedly atomic).
