Macboss,
The throttle response on my Moki 250 Radial is immediate with no lag or stumbling. However, I use a 1 second transition speed and a throttle curve for the following reason. A smoother throttle transition helps prevent the powerful motor and 18 pitch prop from torqueing the plane to the left upon acceleration. In addition, if for example, the engine was slightly mistuned, a slower throttle response might prevent the engine from cutting out and stalling. The same holds true for de-acceleration. The throttle delay and good throttle curve would be beneficial anyone who flies an airplane in a scale like fashion. Slowing the speed of all control servos on an airframe can give rise to much smoother flight patterns.
Regards - Jaketab