I have the Extra from AK.Nice looking plane.I put a Magnum .91 2-stroke on it.1st flight for me in almost 7 years went well until I throttled back to land,engine would not come back to idle.Had to fly around until it ran out of fuel and deadstick it.The srvo tray unglued itself and threw the throttle servo out of adj.I then noticed the covering loose under the landing gear so pull it off to monokote it and the bottom piece of the fuse the gear bolts to came off with the old covering,I saw a place that had a small dab of hot glue holding it.Just watch out for bad glue joints and loose covering.Also,the extra could use a computer radio,the control throws from the instructions are a little sluggish for snap moves and increasing them makes the plane "jerky" in normal flight.As for your ?,Id go with the 4 stroke.That would be cool to see a small cub with that little motor in it.