Well, the CX2 is the easiest model heli in the world. The rotofly is the hardest model heli in the world.

That may seam like an extreme statement, but I assure you that it is based on fact and real world observations.
Oh, there are other counter-rotating models that might be slightly better or slightly worse than the CX2. But as a class, the counter-rotating models mostly fly themselves. I have given demos at our club meetings with Hirobo's version, and I literally took my hands off the sticks and let it hover in front of everyone with no control input.
And the Rotofly is not the worst. It is a Fixed Pitch (FP) micro heli, and these are the least stable, hardest to fly class of helis. Robust? Sure. I crashed my Piccolo, and older FP heli a thousand times. I needed repairs about 20 of those times. But it is the STEEPEST learning curve there is.

Vince