Thank you for your quick answer !
I tried to set the expo on radio, but the problem is that I can't manage to get a very fast rolling rate in the end stick, even with 30-60% expo set on the radio it still feels slow. With too high expo (40% or more) the sensitivity is becoming worse.
What I am missing is this super rate to boost the end movement without compromising low movement stick and mimick a real quad.
The code from betaflight is available (with how the rates are processed in the function "calculateSetpointRate". You can have a look in the code here : https://github.com/betaflight/betaflight/blob/master/src/main/fc/fc_rc.c#L98 ).
It would be a really nice adition to both your simulators to have finer control on the stick movement.
Thank you ;)