Flaxton - if your AA is going to take this task on then surely you have a weight of evidence to support using these funds in the first place. There must have been sufficient numbers of jobs (rather than just the odd one or two) where the winch would have significantly enhanced your ability to provide medical care. If not then it would seem irresponsible to use donated funds on the off chance that you might use the capability.
If all you intend to do is save the paramedic/doctor a bit of a walk then the extra risk is, in my view, unjustified. Will they get paid more for the added reponsibility of winching/being winched and will their extra life insurance premiums be paid by the charity?
Tec-pilot the main difference is that there is a fully established SAR system in UK for onshore work as well as offshore to provide this capability whereas in many areas of Europe there is not.