samba - Dec 2006 - can a combination of samba 4 tp4 server set as AD controiller with a samba 3.x BDC(slave) emulate a MS AD infrastructure ' well enough' right now?

Looking at the warnings about not running samba 4 (tp3) in a working
environment, because of the missing file printing features make me
wonder if one could get away with only using the AD controller features
of samba 4 for now and have a samba 3.x DC, that has joined the samba 4
controlled Active Directory domain, handle the file and print sharing.

How much of an issue would the missing samba4 (tp3) ACLs functionality
and other registry type functions likely be for running such an
'emulated MS' Active Directory domain all under the top-level control of
a samba 4 (tp4) AD server?

Would this be a thinkable thought to have some of the benefits of an AD
domain 'right now', and allowing us to wait for samba4 to be completed
and then do it properly as opposed to being forced to introduce MS
Servers running AD at the top-level right now, and then likely never
getting a chance to switch back to using open source software
exclusively as our NOS?

Has anyone already tried this? Or is there a project out there that
works on this sort of samba 4 AD now, as oppsed to waiting for the whole
of samba 4 to be production ready?

-- 
Urs Rau