A lot, once you get used to that, there is no way you are flying if the device is off.
You dont feel a regular roll, but will feel when pulling g loads, or when approaching stall.
One fair example is I never broke the wings of the tomcat again after buying the device. My flying is more finesse and smooth. Using weapons, dropping flares, ground rolling, air brake out, landing gear operation... Like I told you for me it's mandatory to fly