Some folks have started to allude to it. Size restrictions. No one argues that larger scale planes fly the sequences MUCH better than smaller one's. Add in a little headwind and it only gets worse.
I like the idea of limiting the size of the planes in the lower classes? Scale percentage, engine size, whatever. Try competing in Sportsman with an 25% ultimate bipe and a getting tired MDS1.48 against a 40% FC Extra! Anyone with even a SMALL amount of practice with the Extra is going to present better than the Ultimate will and consequesntly will score better.