It's not a plane issue. I've done beautiful cuban 8's with the Nexstar, Avistar, Dolphin, done them with the Decathlon but the rolls didn't look so hot - engine not broken in, plane not set up yet, etc., and I do them well with the Venus planes of course. High wing planes roll differently than low wing planes, that's the only 'limitation' if you want to call it that.

What happens (specifically) when you do one? Cuban 8 is 5/8 inside loop, so you're STRAIGHT AND LEVEL going into a loop, keep looping until you are at a 45 degree angle down, opposite direction. Slight pause, roll right side up, slight pause, and a 1/8 loop to level, wash, rinse, repeat in other direction.

If it helps, space the two halves of the maneuver out a little bit, so you are doing two half-cuban 8's.

I'm sure you know how much experience I have, but in my green-eared opinion I would say hold off on getting a new plane until you can nail this maneuver - it is pretty much the basics - practicing loops, half rolls, and 45 degree lines. If you are still struggling after breaking it down into two halves, then practice STRAIGHT AND LEVEL flight, practice pulling up into a 1/4 loop without dipping a wing, practice your immelman and enter a 45 degree down line after, etc. You can practice the rolls, loops, and lines separately.

I jumped into new planes fairly quickly, and made the mistake of getting the Decathlon because it wasn't the plane that I wanted. Well, it was for the week or so that I ordered it and waited for it, but by the time it came I wanted something totally different and was incredibly disappointed.

Keep up the practice! I love hearing about people doing aerobatics - they are beautiful! Keep us posted of your progress