Hi CJS
For S_RFC - did you have trusted systems in place. If so, you need to add S_RFCACL unless that's what you mean by PRGN_CUST
Is you SU24 data in the child system and synched? I only ask this as I saw similar post and some notes that referred to authorisation maintenance issues due to SU24 data not imported in child system properly. Here's one of the threads as an example:
http://scn.sap.com/thread/2105640
Regards
Colleen