harmsway, I'd recommending using them, and I do (expo). Expo is a great tool for softening a plane's response around neutral. For example, you have a plane that is very sensitive to control inputs and you want a gentle-handling plane on final approach and during level flying. Expo will do this for you. Dual rates are similar in the effect. You have a plane that is violent on full rates. So, for landing and takeoff - you switch in, let's say, 50% rates. Now you have the same plane but with half of the control response. When you're ready for the aerobatics, switch the rates off.

Dr.1