You're very welcome 
I do not know of any SSO issues in XenForo
http://xenforo.com/community/resources/
From my prospective based upon my experience, I came to form an opinion as to exactly why IPB hides their support forums from the general public (that actually involve support), as opposed to just having it in full view or maybe even using a modification to hide select aspects (if code was their concern).
It was actually a question I originally had before buying into IPB.
Why do they not display something to provide a real world, live, and true demonstration to reveal the actual level of friendliness and support within their community (why do they hide the forums that actually were designed for support)?
It is question I ignored and learned the hard way.
Believe me when I say that if you want to really learn how to develop within a forum environment , you're going to get a lot more support, advise, tips, and even solutions from other developers and designers, here on XenForo. And you can clearly see that even as a guest.
