The Great Planes Cap 580 is a great aerobatic airplane and a fine flyer. Chapman's real 580 is the pinnacle of modern aerobatic airplanes! So, to consider the RY 4 to be better doesn't gybe with reality. I have an O.S. .46 AX in mine, which is a good combination. I would agree it's not a 3D aiplane. However, 3D isn't the end all and be all and this airplane does everything but. 3D planes are generally specifically designed for 3D, they are lightly built with larger control surfaces. Don't own and haven't flown the the RV 4.