This thread started with a question asking about winch-fitted HEMS helicopters in the UK. The question I would have posed would have been "is there an operational requirement for winching by HEMS helicopters in the UK and would it add a cost-effective capability".
If a comparison with HEMS operators in Europe was required one could look to JAA TGL 43, paragraph 1.7.6, where it could be seen that HEC flights (that is both winching and long/short haul) occur in about 20% of the missions - not surprising really as the operational area is the Alps.
It would therefore appear that geography plays a large part; as does the presence of a large transient population conducting recreational sports - which indicates a certain amount of risk.
There is nothing in the extant regulation that prevents winching by UK HEMS operators; it can therefore probably be observed that: the reduction of payload; the additional cost of equipment; and training (which in the UK has to be at HEC Class D Standards), outweigh the potential benefits.
The fact that there do not appear to have been any cost benefit analyses (or none that I have heard of) probably indicates that the sums can be done on the back of a 'fag packet' - or put more scientifically, qualitatively.
Jim