Hey Stoke, interesting question on the crossover between Gymkhana riding and dirt riding, but I'm not sure there is a definitive answer.
The guys over in Japan reckon that you can be good at dirt riding, road racing or fast road riding, but that won't make you good at Moto Gymkhana. On the other hand if you're good at Moto Gymkhana then all those other disciplines are easier as a result. This is certainly true of road and circuit riding, but as I don't do a great deal of off-road riding any more, I can't really say for sure whether it does or not.
Dedicated to the wonderful sport of Moto Gymkhana