two different versions of samba4 on different DC

[David Mansfield]

Is it safe to run two DC in the same domain with different samba4 
versions?  My primary is running 4.0.1 (I'm still not sure what the 
recommended upgrade path is to the latest... or even if there is a safe 
upgrade path) and I'd like to set up another DC with the latest version 
4.0.4.

In general, what is the upgrade strategy (software version wise) once 
there are multiple samba4 DC in the domain?

-- 
Thanks,
David Mansfield
Cobite, INC.