think CRM - expecially if integrated with cockpit - is something BASIC! I'm a certified jar-ops crm/hf instructor (took in Sweden) and I think every cabin crew MUST be trained as well as cockpit crew. It must not be considered as a routine training , expecially now that re-enforced doors divide cabin crew from cockpit. Anyway courses give a direction on how to cooperate on board, about matters which are not usually discussed during recurrent trainings or basic courses.
My opinion is not to undervalue the importance of a good CRM preparation!