You can use existing version if you are too exited.
I did it today with usa version and all is fine. No wipe, just backup with helium (not yet rooted)
All app are working, a little issue is app can not write to sd card with 4.4.2.
Not a big problem for me.
Actual phone : Nexus 5 16Go Red (old phone : Samsung Galaxy SIII)
Actual tablet : Samsung Galaxy Note 10.1 2014 Edition SM-P600 stock rooted with xposed modules (old tablet : Samsung Galaxy Tab P7510)