The thing is that helicopter handling varies a lot with different settings...
For instance rotor RPM greatly affects it's responsiveness and stability, throttle-pitch curve changes climb-descend performance, exponential roll and pitch increases handling precision...

There are so many settings which affect performance and handling that it's really hard to set it just right.

I just got my T-rex 450 clone last week, put it together, and when i flew it was quite different than what i experienced in realflight G4.5.
The helicopter was much less responsive and collective pitch was soo sensitive.

But now that i have to wait for my tail blades and shaft due to a completely avoidable and unnecessary mistake [&o], i went and changed settings for my helicopter in the sim, added light gusty wind, and the flying experience was almost the same as flying the real thing!