Yes, pretty much all Joomla extensions rely on the core Joomla user session. If not, they should You do not login to DT Register... or JomSocial... you login to Joomla, regardless of which login module or profile management extension you use.
Hi
Jomsocial is currently at 2.6.2. We are fully tested on 2.6.0. We're not completely done testing for 2.6.2, however we are not seeing any bugs yet. When 2.8 comes out, we will work to maintain our compatibility though we can't guarantee it without knowing what is changing over there.
Thank you for the fast response! You guys have the best features of any event software currently on joomla and I would really look forward to using DTregister again for this new project.