I second that. Post PPL I went to New Zealand just to learn the basics of non airfield landings/flying. After PPL I felt unprepared for this environment (and I had great instructors. Just the syllabus is lacking....
I think its worth mentioning that going inadvertent IMC in a light helicopter not approved to fly in IMC (Not just R22s or singles) with a pilot who has only had the basic instrument flight training is a world apart from an instrument rated pilot having pre planned a flight taking into account minimum altitudes for terrain clearance, freezing levels etc, flying a machine certified to fly IMC.
I think the 5 hr PPl instrmnts was useful and made me safer at the time.... but the above point should be impressed on students equally strongly... i.e What you don't know is this.. etc etc... e.g keeping yr speed/failing AH etc.