Samba3 to 4 migration & RFC2307

[Adam Tauno Williams]

I'm looking at migrating to S4.  But I'm a bit stumped on how to get
from A to B.

I have a Samba 3.x PDC with an OpenLDAP SAM backed that also uses
RFC2307 [via nss-ldapd].  Multiple non-CIFS services/hosts use the
OpenLDAP provided user 'database'.  I need to keep the user->UID/GID
mappings.  

1.) Does Samba4 have any support for RFC2307? 
[Windbind for S4 seems to work fine, using its internal idmap].

2.) Is it possible to migrate an RFC2307 user database  [idmap] into
S4's idmap?

3.) Does the myldap-pub.py script I've seen mentioned support this?
[BTW, neat looking script - terrible name]