With the higher deflections or throws of the higher rates, you want more expo when using high, which is why I use about 50% for high rates.

You do not want to do this to the rudder to the same degree, or else you'll find that if the plane yaws at takeoff, you'll slam the stick and overcontrol.

I typically use lower expo on the rudder to give me better, but less "finer" control during takeoff.