ORIGINAL: fly24-7
If you look at the flight video on Horizon for the new Meridan, it's no slouch. It seems if you want 3D grade performance, you need to be in the 4-6 pound range. 7-8 pound range seems to result in good basic aerobatic performance.
That is my experience. I first had the engine on a 7 lb 4 oz. airframe and it had great vertical performance. It is now on an 8lb Meridian and it flies like in the video, a very good aerobatic performer. If you want 3D, then you'll need a lighter plane.
Dave