Power, cost, and weight are all about equal between a C50 and a Pletty Evo. The outrunners unload a little more in flight, and are much much quieter in the air.

The biggest difference is maintenance, my oldest Evo is now in its 4th season and has never left an airplane for any maintenance work whatsoever, any inrunner with gearbox will over time require significantly more time spent ensuring the gearbox is greased properly.

Also outrunners in general can tolerate more heat and therefore are better in very hot climates. They also can typically use a much broader range of propellers effectively, because they can unload better than a gear drive motor.

The biggest difference it maintenance....personally if I want to work on motors I will get a YS. IMO there is no advantage to going to electric if you have to grease gearboxes every 50 flights....its a failure point and people have lost rounds because of it. So why not just continue to run glow in that case? With my Evo, I have gone for 3 full years with not a single minute spent maintaining a motor....thats the advantage IMO.