I have flown mainly pattern for the last 4 years but I do 1 or 2 imac contest every year when there is no conflict. I love the way my pattern planes fly. I don't fight them. My 25% Cap is a good plane but doesn't fly near as well. It is not as stable, the wind has more effect on it etc. They are about the wingspan and weight.
I can't see me build a 100in wingspan plane just to get the same behavior. The room it would take and the cost cannot be justified for me. There is also a lot of different models to choose from in pattern. You are not limited to Cap, Extra, Sukkoi, Edge etc. You could be competitive in the first 3 classed with a 90 size plane if you practice properly. Even if you go to the 140 size plane, you will need only 5 or 6 servos, 1 batterie pack, a motor that could cost about 300$. It's not bad.
Don't forget that Imac is not 3D. The only 3D in Imac is the freestyle and even then, is can't be done below a minimum altitude. What you see at the TOC or in some website and magazine is not Imac. Real 3D could also be done with a 40 size plane like the Madness. I could touch the tail anytime, hover until it runs dry, fly very slow, etc. And the complete plane is about 800$. I am not broked if I destroi it. It is so light that you would need a big crash to destroi it anyway.
I will be building a new pattern plane next year and I know it will be equivalent of anyone at the world level, and I could pay for it. On the other end, I cannot pay for a TOC plane (or I don't want to pay for it)
It's a very personnal question.

Xavier
http://xavier-avion-rc.freeservers.com/