At the moment I believe that almost all the AAs/HEMS conduct what is, effectively, flying from point A to point B in Day/VMC. Therefore, even in this very narrow role there is no all weather, day/night provision of a AA/HEMS service.
When blowing their own trumpets whilst waving a collecting tin under our noses, the fact that they shut up shop when the weather gets bad and/or it gets dark, leaving the military (RN and RAF) to do the more difficult stuff, is conveniently ignored.
My question is, why not learn to walk before you try to run. Develop a day/night/IMC med-transfer capability first and then build on that?