Hi Crispy,
As you can see by my changed alias (vautrin2), if a user changes their alias, it changes it for all posts--also, it seems that not all alias options will update (e.g. I can't change my alias back to vautrin). The use case I had in mind would be a per post hide my identity bit.
A thought along these lines is that someone could of course deduce someone's identity through post statistics--unlesss posts marked as hide my identity were excluded from stats.
Anyway, thanks again for the incredible job!