ORIGINAL: MinnFlyer
I can't think of a single downside.
I know some kids who are outstanding 3-D pilots. Last year, one of them had a flameout with plenty of altitude, but without power, he didn't know how to ''fly'' the plane in. He stalled it all the way to the ground.
I saw a similar thing happen with a 50cc Yak. The pilot is an excellent flyer, but has only flown small foamies and large gas 3d planes. He had a deadstick and stalled it all the way down to the runway and destroyed the plane. Knowing how to fly with no power is definitely a good thing.