I agree with m@winlow.co.uk - if hybrid powertrains for aircraft made sense then there would be data that says so. The above article makes no attempt to describe the improvement of hybrid versus conventional. There should be a full accounting of masses - (engine+batteries+motors+propellers+fuel) versus (engine+propeller+fuel), but again, as in the past, there is no accounting for why/how a hybrid improves utility of aircraft. Certainly, it can be argued, a more complex system has more failure modes. Also noteworthy is the trend for turbine engines to be less-efficient as they get smaller.