Your D/R are the percentage of the EPAs programmed for each channel.

Correct me if I'm wrong, but I don't think you can get any more throw than the EPA's you program by using Dual Rates. In other words, D/R don't go higher than 100%.

EPAs could be used to set up your radio so that there is no mechanical binding in the linkages.

Then set up the D/R to suit your flying style in different conditions. Since the D/R are switchable, they can be switched back and forth during your flight.

All of this is controllable from the radio, and you don't have to revisit the linkages.

Also know that HiTec radios EPA's range +/-125% for +/- 60 deg.