[Samba] samba 4 for new authentication domain?

[Morty]

The various pages about samba 4 warn about rough edges, upgrade, file
services, and print services.  I have some domains that have never had
a Windows domain that now need Windows AD authentication.  I don't
need file services and print services, and upgrade is not a problem.
Is samba 4 ready for this use case, or should we still go with
Microsoft's AD?

Thanks!

- Morty