The military should not lose SAR for the simple reason that it maintains a centre of excellence for SAR in the military sphere. This knowledge is then propagated throughout the fleet as people move. Whether or not the civvys can do it better is immaterial, as well as dependant on what you consider better. Cheaper certainly.
And what your IFR fit has to do with it I have no idea. RN SAR Cabs have no DME, no VOR, no ILS, and I never had any cause to want one. If where the casualty is has one of those, you do not need a SAR cab.