apbonura,

I have the Great Planes Extra 300S, 40 size ARF with an OS 70 Surpass II on it.

It is a very nice flying plane and would be fine for Basic and maybe Sportsman IMAC sequences, however, in my opinion it isn't suited to fly 3D maneuvers (hovering etc.). Also, it wouldn't be a good plane for IMAC sequences above Sportsman. For this you really need a bigger, more stable, and more powerful plane.

Keep in mind, if you're just getting into IMAC you don't need to do 3D now anyways. The first step is to start learning precision flying with the basic sequence. I have no idea what level you're at, but if you haven't flown precision before this alone will keep you occupied for quite a while.

Good luck,
KeithB