I give up. What is so special about Persona???
I have been using my own home-grown version of the same thing for many years.
And ASP.NET provides something virtually identical as its means of user authentication.
Personally, I would trust my home-grown version more, simply because I wrote it and I *know* that it doesn't have some back door in it that is sending all my user's email addresses and passwords to some central site for collection and later use in Phishing or worse attacks.
An optimist sees the glass as half full.
A pessimist sees the glass as half empty.
A realist drinks it no matter how much there is.