The whole multi-use HEMS-Police-SAR helicopter thing was discussed at RUSI in April 2012. There were very experienced people there from all those helicopter disciplines and several countries.
The multi-use idea did not gain much traction.
Some UK air ambulance types were getting very excited about long-line and this led to much rolling of eyes amongst those who have a grasp of the HEC accident rate in other territories. The Norwegian air ambulance guy emphasised the training load for their long-line work (10 training sorties per op sortie) and that its purpose was to insert a paramedic before the SAR helicopter arrived.
The Poles were developing a system for MR to abseil from air ambulances but again that was about insertion of specialist help at the casualty location.