The capability statement for patient says that the referral mgmt task is supported and the patient task is supported.  Both should support version queries since version is important in task mgmt.  Also, it seems that the referrer, the patient, and the recipient, as well as an intermediary can update the Task.  I am concerned that the Task overall definition will be overridden when the main purpose of the Task update function is to update only fields related to the state transition and not the definition of the Task itself.  An operation seems safer.