I bought a hyper viper about two years ago. The engine ran great after about two tanks. It is fast in level flight, but kind of shaky in maneuvers. It's on the wall in the living room now. If past experience with cox planes has taught me anything, it's that they degrade from fuel exposure after a few months of inactivity. I doubt if I will fly it again. I personally think the older super chipmunk was a better out of the box flyer.
I remember at the Lake Charles Nats in the late seventies the Cox people brought an 18 wheeler full of planes and they would let anyone that was interested take a stab at flying them. I've never seen so many crashed planes in one pile in my life!