And on the other side, IMAC planes can be larger (usually are but don't have to be), so they are easier to see, fly, and judge. They can be flown slower and farther out than a pattern plane so there is a lot more time to think between maneuvers. As for coupling, most of the modern designs have reduced coupling to a bare minimum, and what remains can be easily mixed out with the radio. The large size also allows the use of fuel efficient, clean running, and very reliable gasoline engines - no flameouts means the airframes don't suffer an early death.