There were issues for me when I transferred all FSMO roles to Zenyal's ADC, copied the sysvol directory and shut the PDC for good.
The GUI still thinks it's an ADC. That means that I am unable to activate Roaming profiles and set the home directory letter via the GUI and when I create a new user there, the profile path and home directory aren't properly mapped. Since then, I have been forced to create all new user's links through Windows' RSAT. Unfortunately, I hadn't found any solution to the problem and eventually gave up.
I forgot to mention that all the other domain functions work well, incl. user authentication, samba shares, GPOs,...