There is plenty of technical data here and from an overview it would seem that helicopters like cars are heading for diesel power as the better way of powering small light helicopters.
I have to admit that I prefer the diesel car to it's gasoline brother for the better fuel consumption, longer life and better torque. Emissions also are environmentally more friendly.
My question is 'Who will be the first manufacturer to provide a diesel (Jet A1) powered helicopter'. Will it be Frank?