In principle, Persona is great. Not storing passwords is awesome, a non-FB/Google/Twitter identity option is important. I would encourage you, though, to look carefully at your login completion metrics. I implemented Persona on my site ( http://www.sixquestions.co ) to have a pure email option and although users clearly prefer it, about 35% complete the Persona login flow successfully. That's 10 points lower than our…
There's 2 issues with persona. 1) users don't already have a personna account setup. They're used to hit their "login with FB/Google" account instead. They don't know that persona is better privacy-wise. So for many, it's just friction. 2) persona login sometimes appears slightly slower
We definitely need something like Persona but I share your concerns WRT friction. Chicken meets egg.
[1] http://identity.mozilla.com/post/56526022621/what-is-an-iden...
[2] http://identity.mozilla.com/post/57712756801/persona-makes-s...