samba - Jul 2013 - Upgrading samba3 to samba4 on a new server, and running them both at the same time

With relation to this page:
https://wiki.samba.org/index.php/Samba4/samba-tool/domain/classicupgrade/HOWTO
I would like to upgrade to samba4 on a new server, but would like to test
it all out before finalizing the switch.
My question is, can I copy over my tdb and smb.conf files (as mentioned in
the above link), and then upgrade to samba4 on the new server, while
staying on the same subnet of my network?  In other words, have both
servers live at the same time, on the same network? The domain name and SID
would be the same, but the host (netbios) name of the two samba servers
would be different.
I've gotta say, this sounds like a Very Bad Idea, and I can't imagine
anything good coming of it, but hey, maybe it would work? Or maybe I could
make it work with some slight config changes on the new server, during or
after the upgrade provisioning?

What I'm trying to avoid is having to physically set up a test network that
is completely isolated from our live samba3 network, in order to test
everything out.  If I can run them both on the same network, it would be so
much easier for me. (Our server closet is pretty small, and the thought of
physically wiring up a different switch with test workstations, etc, is not
something I want to do if at all possible).

Thanks for any input.

On Tue, 2013-07-23 at 09:46 -0700, Scott Goodwin wrote:
> What I'm trying to avoid is having to physically set up a test network
that
> is completely isolated from our live samba3 network, in order to test
> everything out.  If I can run them both on the same network, it would be so
> much easier for me. (Our server closet is pretty small, and the thought of
> physically wiring up a different switch with test workstations, etc, is not
> something I want to do if at all possible).
Use a test network.  

Once clients see an AD DC, they won't like the old server, particularly
for NT System Policies, or if they change their machine account
passwords.  Additionally, the DCs will fight over the PDC role netbios
name. 

Andrew Bartlett

-- 
Andrew Bartlett                                http://samba.org/~abartlet/
Authentication Developer, Samba Team           http://samba.org