That is an interesting question Franz. I'm sorry I don't have an answer for you but I am having a great many issues with my DSfW and looking at possible solutions. 

I have an issue where certain applications will not run if a user logs onto their workstation using a DSfW domain account but the issue does not exist if the domain controller is a Windows server.

I'm not yet ready to abandon DSfW completely but I was wondering if I could introduce a Windows Server into the mix and make it a domain controller thereby eliminating issues I have when accessing my DSfW servers.

I'm currently thinking about 3 ways to do it. One way is to join a 2012R2 server (this version doesn't enforce DFSR yet) and promote it to a DC and then remove DSfW. This is a scenario that seems to work with pure samba, hopefully it also works DSfW samba.

Second way I have in mind is to create a fresh domain with a current samba (specifying the old DomainSID and DomainGUID is possible with samba) and transfer the user data via LDIF. After that is done, continue along the 2012R2 route.

Third way would be to create a fresh AD domain with a current windows server, fill in the users via IDM and then add the old users SID to the new users SIDHistory.

All ways are likely not easy...

I'm currently thinking about 3 ways to do it. One way is to join a 2012R2 server (this version doesn't enforce DFSR yet) and promote it to a DC and then remove DSfW. This is a scenario that seems to work with pure samba, hopefully it also works DSfW samba.

Second way I have in mind is to create a fresh domain with a current samba (specifying the old DomainSID and DomainGUID is possible with samba) and transfer the user data via LDIF. After that is done, continue along the 2012R2 route.

Third way would be to create a fresh AD domain with a current windows server, fill in the users via IDM and then add the old users SID to the new users SIDHistory.

All ways are likely not easy...