Low/high rates are used for various reasons. Usually though, most people use low rates for normal, mild flight and high rates for aerobatics. I also like to set some planes up with high rates just for take off's and landings. In those cases I may just increase the elevator and/or rudder throws. If you saw me land though you'd swear it doesn't help. Of course, that's pilot error not plane or radio set up.

What kind of plane are you flying? If it is a typical trainer, there may be no need to mess with dual rates at all right now.