Maybe, as F43 mentions, IF the various 'incidents' suffered by S/E aircraft that were, in fact, power loss ditchings, were recorded more fully, the statistics might favour twins.
At the end of the day, I don't think anyone is advocating using an S-92 where a 206 currently operates. However, as the accidents/incidents, referred to here, clearly show, had a 427/355 been used in preference to a 206/407/120, then they would probably not have resulted in ditchings. It's not a difficult concept to grasp!
So we've seen the twin vs single debate going on, how about the turbine vs piston? Think how much money all those 407/120 operators could save by using R-44s