Thanks for sharing your interest in this topic, I love tech topics also. I keep up on the technical news and occasionally I have thought about including electric topics here as well. They seem to have an application to certain unmanned science and surveillance aircraft and to light sport airplanes, for which they are ideal. The immediate future is in unleaded gas and possibly biofuel. My understanding is the pure electric is ideal for use in light sport airplanes. It's a lot like the choice you have with surface electrics: electric works and works well as long as you stay a limited distance from power. It has numerous positive qualities like reliability, responsiveness, quiet, and so on. But you also have to trade speed for endurance in a severe balance. You can go fast with lots of acceleration, or you get enough endurance to go some fraction of the distance of gas. Therefore it is not mature technology until a better battery is designed. Electric is very good for use in light airplanes for flying without the roar of the engine. Electric powerplants have many other great qualities as you know. The future is bright for electrics, no doubt about that. However, there needs to be a breakthrough in battery technology before they are competitive with combustion.

The hybrid is an attempt to alleviate the battery limitation by letting some gasoline ride along with higher energy density. It's not a bad idea for small airplanes and it certainly could be done, but hybrids will have to go through an enormously expensive development-certification cycle, one the GA consumer cannot support. We first need to solve the unleaded gasoline problem then we can think about other engines. Cheap gasoline motors brought the wonder of flight to the average working person but even without the cost of developing a new powerplant GA airplanes have gone beyond the reach of the average consumer. The light sport airplane is an attempt to remedy this problem. So, while it may be technically possible to engineer a hybrid airplane and we already actually have electric LSAs, the hybrid-electric GA airplane in 4 to 6 seats would almost certainly be a miss owing to cost. Engineers have to look at cost in order to propose a development program. You would have to sell many more airplanes than GA manufactures in a given time to make back the cost for development.