Well years ago used to fly a mil 341 in IMC with no sas or come to that sat nav or nav system, don't include mini tans as it never seemed to work when it was wet outside. How many accidents did the UK mil have with a singe engine in IMC ? The adage about a twin is rubbish when you look at the number of engine failures helicopter have, greater percentage of accidents are CFIT then engine failure
The UH-1 in the German Air Force and Army flew in IMC on a regular basis and I never heard of an forced AR in IMC due to engine failure. But there was an Army CH53, which lost both engines ( icing ), popped out at 500' GND and made a safe AR-landing in the grass...
skadi