Aser,
Months ago I posted the performance of three hypothetical helos, a one-engine one, a conventional two-engine one, and a two-engined one that could hover on one engine. The cruise range hit that you take to have OEI hover is not at all understood by pilots, I have nearly given up trying to explain why. But here goes!
Turbines are awful at part power, so the less power you are pulling in cruise, the very much worse your fuel burn is. For a given cruise power, the fuel used is at least 40% higher if the helo has OEI hover, I said. Thus, the 100 pph fuel flow for the 139 vice the 600 to 700 for a 412 or 76.
More power does NOT mean better cruise performance!! Thus the "cost" of having scads of power in an OEI condition is paid for on every cruise mile, and in the loss of revenue for meduim distance flights, as well as every overhaul, and every insurance payment (you pay for the cost to replace). For no measurable increase in safety.