I agree with Mike McConville. The most intense form of concentration I have experienced is flying in competition. Anyone can fly an IMAC sequence. And any good 3D pilot can fly an IMAC Advanced or Unlimited sequence. The real challenge comes not from just flying the sequence, but in flying it well enough to win. Competitive flying is a whole different ball game. I have fun flying 3D stuff, but pretty much with my foamies since I don't get much more out of it whether the plane is big or small. However, for me, nothing beats the challenge of trying to execute a string of flights with enough consistent precision to eek out a win over guys that fly as well or better than I do. I personally enjoy working on my airframe and radio setup to get the max precision performance out of my plane. It's just another facet to this sport that intrigues me.