A few more comments about pattern evolution:
Initially, with the introduction of Aresti style pattern in 1984, fliers thought they'd need bigger slower planes to stay in the box. wolfgang Matt's Joker is a good example. He had been flying an Arrow which was one of the fastest of the old style pattern designs - I loved mine!! At the 1985 FAI WC the Japanese showed up with fast airplanes only slightly larger than previous designs; such as the Aurora which was preceded by the Cosmos. The 150 meter boundary was not very stringently enforced. The Japanese flew closer to 180 meters out. Designs changed to be larger (for .60s), but fast (thin horizontal surfaces) such as the Mistress or the Summit or the Jeckyll. Naruke Shpwed up at the 1987 WC with his YS 1.20 powered Silent ST design and impressed everybody. 1989 was the last WC where both 2-stroke .60s and 4-stroke 1.20s competed in relatively even numbers. Aircraft performance varied tremendously. Tony Frakowiak had his Fyg Leaf .60 powered biplane. He flew precise, but quite small maneuvers. Wolfgang Matt had his Saphir .60 design which he retrofitted with the YS 1.20. It was a rocket - FAST - it accelerated in the verticals and the maneuvers were HUGE. I was lucky enough to attend. Probably the biggest variety of flying styles ever.
The 2meter, 5kg, unlimited horsepower rule and continued refinement of the aerobatic sequences has driven current designs. Large fuselage volumes to enhance rolling maneuvers at lower speeds. Smaller, thinner, double tapered wings to reduce drag and improve snap rolling maneuvers.
Who knows what's next...
My 2 cents :-)
Will B.