[Dovecot] Migrating Emails from 1.0.15 to 1.2.2

I need to copy some email storage from a Dovecot Server running 1.0.15
into another Dovecot Server running 1.2.2. I know that I can use imapsync (perhaps this is the proper way)

But I was just wondering, if I can just run Rsync to do that transfer: Will I run against some incompatibility formats between these two versions?

M.A.