Do ZCS versions have to match with a migration?

Hi,

Rather newbie question, sorry, but when performing a migration, do the versions of Zimbra itself have to match?

I am trying to perform the following:

Source machine:
Zimbra 6.0.16
OS: Ubuntu 6

Dest machine:
Zimbra 7.2.6
OS: Ubuntu 10.04

And wanted to know if I can do this in a single step? Or if I need to install Zimbra 6.0.16 on 10.04, compete the restore with ZxBackup, then upgrade to Zimbra 7.2.6 just as I normally would?

Many thanks