I used to fly SAR in a twin engined helicopter (S-76, with no single engined hover performance). Immediately prior to winching we always confirmed in the final crew safety brief what actions we would take in the event of an engine failure. The plan varied because of the actual rescue situation. If winching from a hillside we tried to have an escape route to fly away from, hopefully winching anyone on the cable safely inboard, or placing them on the ground. If it was over a sea vessel it was sometimes a matter of damage limitation! The very last part of the brief was normally to remind the winch operator that it was his decision whether to cut the winch cable or not. That was because as pilots we couldn’t see the winch (on the starboard side) due to the aircraft design. The normal intention was to place any persons on the cable on the ground, move away then land….how successful all of that could be in practice was only conjecture. If the winch op didn’t fire the cable cutter and the pilot really had to, he could do so. Not to be done lightly!
As far as flying people as underslung loads is concerned, it cannot be done (at least, not in U.K.) without a CAA written permission. I know one pilot who unknowingly flew a worker in an underslung load net for a short distance and having owned up to the CAA found himself prosecuted and heavily fined.