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.
On the flip side, this is exactly how I learned to fly. When I "graduated" to glow engines, I was shooting landings with my instructor. My engine quit and he started to grab the box. I told him, I knew how to land a plane with no engine and so my first solo landing was dead-stick. Picture perfect, just couldn't taxi back to the pits.