Hi,
I use K2.5.7 with community Builder 1.8 and it works very great BUT when we click on "my page" after registering we are routed to the Cb profile page wich don't offer the k2 items management like classic K2 my page. So in my mind there is 2 possibility :
-Disconnecting (hack I think) conditionnal router to the CB profile page
-having a Cb'k2'tab in order to 1/manage our article 2/ offer the possibility to have our k2 article in the profile page like the classic Author page in CB.

I think it's weird than it doesn't exist....

There is a setting for disabling Community Builder integration in K2 global parameters.