Watchdog
I will not say that they all will fail the transition, but most people I know who have gone Boeing/MD to Airbus, have found the course difficult. The main reason seems to be that the way of "thinking" in Airbus with regards systems and procedures etc, is a lot different from Boeing/MD. (No slanging off of which is better).
I dare say that a lot of the Jet* boys will find the same.