Well, it appears to me that everyone is correct ... to some degree. However, the law, in this case, appears to be an ass.
As MaxHelixAngle says "a switching call is only required if Centre will not or cannot be monitored"
As Rotorblades says "As another part of ERSA enroute says IFR in class-G airspace have to be in contiuous two-way communication with ATC."
As Bula says "I'll respond, when I feel all bases are covered, and not before. Aviate, Navigate, Communicate."
The trouble is that the rule is setting everyone up for failure. The rule might need to be changed. Perhaps a specific ATC initiated frequency change to CTAF at x distance or x level. The ATC's responsibilities should then end. The the Pilot can also monitor centre, if he wishes, for extra SA... as he can also monitor CTAF earlier, if he wishes.