What do you think? Is it worth to share this in any howto? Do other
people still use samba pdc? Would it make sense to integrate this in the
kolab-webadmin code?

yes, that would be great. Doesn't matter where you look at the IT World. You need a Central User Management,
in the most environment (Office) there is a AD DC System installed. And with Kolab you get at the moment a Second User Management, which of Course make thing complicated.

Could you Please explain how you done the Integration ?

Best Regards